The Zygon Invasion






Place of Origin:


Affiliated With:

UNIT, Operation Double


Petronella Osgood’s sister
Petronella Osgood

First Seen In:

The Day of the Doctor


Death in Heaven
The Zygon Invasion
The Zygon Inversion

UNIT: The New Series




Power Cell
Death in Geneva
The Battle of the Tower
Ice Station Alpha


House of Silents
Square One
Silent Majority
In Memory Alone


Call to Arms
Tidal Wave


The Dalek Transaction
The Sontaran Project
False Negative


Game Theory
Code Silver
Masterof Worlds


Hosts of the Wirrn
Breach of Trust
Open the Box


This Sleep of Death
The Power of River Song

Special Releases

The Eighth of March
The Legacy of Time
The Sacrifice of Jo Grant

The Twelfth Doctor Chronicles

Field Trip

Doctor Who Annual

Yes, Missy

Target novelisations

The Day of the Doctor

Titan Comics
Doctor Who: The Twelfth Doctor

Clara Oswald and the School of Death
Robo Rampage


The Lost Dimension

Main Actor:

Ingrid Oliver


click on images to enlarge


Petronella Osgood was a scientist who worked for UNIT, acting in a capacity of a personal assistant to Kate Stewart, in the early 21st century.

An admirerof the Doctor, she eventually met the Time Lord during the infiltration of UNIT by Zygon invaders, which was resolved by the Eleventh Doctor joined by his tenth and war incarnations. (The Day of the Doctor)

The original Osgood and her Zygon double became indistinguishable from each other to everyone else. They refused to identify which one of them was Zygon and which was human. (The Zygon Invasion) One of them was killed by Missy. (Death in Heaven) After a Zygon rebellion was ended peacefully, the Zygon rebel leader Bonnie took on the form of Osgood to maintain the peace. Both Osgoods still refused to identify if she was the human or Zygon version but promised to identify if she was human or Zygon one day when no one would care anymore. (The Zygon Inversion)


Osgood came from a family of science geeks, (Earthfall) and was raised by a single parent (Narcissus) with her sister. (The Day of the Doctor)

She studied at King Henry’s University in London, (Power Cell) and achieved at least one PhD. (The Sacrifice of Jo Grant) She was recruited into UNIT because of family connections, (Power Cell) via a relative she assumed John Benton would have met. (Call to Arms)

At some point, she met Sarah Jane Smith. (The Day of the Doctor)


Osgood often created pieces of technology to aid in UNIT’s missions, typically to stop the soldiers from shooting at aliens, much to Kate Stewart’s delight. She tracked a set of energy units falling to Earth and warned Vikram Shindi about it. (Vanguard)

Together with Lieutenant Sam Bishop, she was deployed to the Gobi Desert in Mongolia in search of a Nestene energy unit. She had created a holographic image projector from alien technology. (Earthfall)

She tried to examine the energy unit using all the techniques she could think of. Kate also told her to examine one of the 3D printers. When the Nestene escaped the energy unit, she discovered that the Nestene could combine through the internet. (Bridgehead)

She created a new weapon to destroy the Autons and was able to free Captain Josh Carter from Nestene control. (Armageddon)

Osgood enjoyed reading files on The Doctor’s exploits, and idealised several of the Doctor’s companions. (Call to Arms, Tidal Wave)


Osgood was investigating a Silurian nest near Scafell when they started to attack. She managed to escape to John Benton’s pub. She tried to contact UNIT HQ but barely got a message through to Josh. Noticing that the Silurians retreated when Terry Waring’s car blew up, she devised a plan to burn the beer cellarof the pub and create a backdraft to halt the Silurians’ progress. She then escaped in Bessie. (Call to Arms)

She was sent with Jo Jones to investigate ‘Project Charybdis’. She donned her own version of the Third Doctor’s velvet outfit. Whilst there, the project was hijacked by Anthony Burmaster to get to a Sea Devil base. Before the Project was exploded she managed to escape. When Jo decided that she should continue The Doctor’s work she got Jo to the Sea Devil base. She later stopped Kate from destroying the Sea Devil base by noticing that the tremor wasn’t a weapon but the base collapsing. (Tidal Wave)

She went with Kate to a Silurian nest in Greece whilst there she met some dormant dinosaurs. In the nest she was looking for a device to control Krellix’s hybrids. Tryska used a machine that induced fear into her, and she relived race memories of the Silurians and started to run around the base. Sam later found her covered in a liquid and regressed to a primitive state. But in that state she found a way to stop Tryska before the base blew up. (Retrieval)

She realised that the Silurians must have been breeding dinosaurs in a breeding programme for millennia. Managing to get to London, she got to her lab to find a way of disarming the Silurians and not killing them. Jo started to help her in the work. She eventually found a possible solution for stopping the dinosaurs the Silurians rode. She was able to disarm the nuclear weapons that Kalana had armed. After the defeat she went with Jo and Sam to South America in order to return the Sea Creatures back the Sea Devil base. (united)


Osgood was present when the TARDIS, with the Eleventh Doctor and Clara Oswald inside, were brought to the National Gallery in an effort to understand what had happened to several paintings in the Under Gallery. The Doctor took a liking to her long multi-coloured scarf, which was strikingly similar to one he wore in his fourth incarnation. She displayed a type of hero-worship belief in The Doctor, twice “praying” to him to save her during moments of danger.

On The Doctor’s orders, she and fellow scientist McGillop analysed the stone dust in the Under Gallery and eventually realised that the dust on the floor was the remains of the statues, which had been smashed by Zygons that had escaped from the paintings in order to hide. She was able to escape from them, although she was duplicated by one of their numbers before she got away.

She was asthmatic and often forgot to use her inhaler when needed, especially when over-excited, often being reminded by Kate when she started wheezing. The Zygon who took her form disliked this, annoyed at “getting one with a defect, ” and promptly took her inhaler. When she escaped from this Zygon by tripping it with her scarf, she reclaimed her inhaler.


Osgood was in the Black Archive with her Zygon version when Kate threatened to destroy London, rather than let the alien technology in the archive fall into Zygon hands. Like the other humans and Zygons in the room, her memory was temporarily cleared by three incarnations of the Doctor, so that she could not recall whether she was the real Osgood or her Zygon duplicate. As peace talks ensued, she realised who the real Osgood was when the Zygon duplicate began wheezing and did not have the inhaler. She gave it to the Zygon version, and both Osgoods agreed to keep their discovery a secret so as not to disrupt the peace talks. (The Day of the Doctor)


After going to a pub quiz with Jay Roy, she was tasked with working out which pieces of UNIT property Lyme Industries had managed to get their hands on. She later asked Jay to help her in her work in order to work out what was kidnapping people. She started to show Jay the ropes but didn’t get too far when a Tengobushi attacked. Jay decided to protect her and detonated a bomb in her flat killing himself in the process. (Power Cell)

When she went to Geneva she decided to visit local Galleries, and she was followed and attacked by Dokan. She later went with Kate and Grant Avery to investigate a set of murders on a French mountainside. Going back to Geneva to analyse some secretions but was attacked by the Tengobushi but was save by Josh. She realised that the Tengobushi wanted her for her knowledge of an Alien artefact and used this to get into their ship. (Death in Geneva)

She and Kate had to fly their plane after the Tengobushi killed the pilots. She then investigated the Kamishi energy cell in the surroundings of the Black Archive. As part of her experiments she accidentally released some power that caused some earth tremors. After the Tengobushi released an energy barrier around the Tower, she released the Raven’s to observe their advance. During the attack she was trapped in the Archive, Josh managed to get her away but managed to get her first to the Jewellery room and then to command centre. She managed to work out how to use the energy cell and weaponised it to aid their escape. (The Battle of the Tower)

When they were under lock and key under Peter Latcham’s orders in UNIT’s base under the Rock of Gibraltar, she managed to hack into the base’s computer to get their release. Whilst at Lyme’s base in Antarctica she worked out a way to destroy the generator and destroyed it with the help of Dokan. The Kamishi questioned her about her actions. (Ice Station Alpha)


Osgood received a panicked call from Colonel Shindi who detected something near Helena Faversham’s residence. While she was tracking the Silents she kept forgetting the positive readings, and after she was attacked by the Silents shesoon forgot. She then questioned Faversham using a truth serum. (House of Silents)


She was working on a universal translator which could understand Axons and Sontarans. She helped Bishop to discover what happened at the Faversham estate. She later worked out a simplistic way of remembering the Silents, by writing stuff down. Investigating the people that went to Faversham’s home, She started with the ones closest to her but they all disappeared. She and Bishop tracked Derek Butler but he was snatched from under her nose. She then looked through all the videos the people she was looking for had made and found subliminal messages to get the UK population to trust Kenneth LeBlanc. (Square One)

A month later she had to brief the rest of UNIT about her solution to getting the rest to remember the Silents. She had created a pairof sunglasses which had 360-degree cameras which could give them all views of the Silents. She called the Silents “Edvard”. After she stole Carter’s laptop, using the same techniques the Silents used, she found a large order of guns and explosives he had ordered. She also used it on Heston to find out where he had taken the things Josh ordered. She then tried to stop Josh from killing LeBlanc but couldn’t, so knocked him out. (Silent Majority)

She went with Bishop to the UNIT satellite to fix something on there, but they were knocked unconscious upon arrival. She started to explore the space station and found a Silent on-board. They were being controlled by the Silents and exposed the spy satellites of all the governments of the world. She tried to get the Telokni ship to stop shooting them, but couldn’t and had to escape. (In Memory Alone)


She and the team flew to South America on intelligence that a local resistance force had obtained alien technology. There they met resistance leader Captain Maria Gonsalves and discovered she had a captured Dalek in her secure bunker. While Kate and Shindi searched the jungle for possible other Daleks, Osgood and Josh searched the base. They discovered a series of rooms containing human weapons augmented by alien technology and were captured by Gonsalves. Held captive with Kate, in the bunker, they both discover Gonsalves was part of a worldwide auction house of alien technology and weapons. Having re-entered its casing The Dalek kills Gonsalves and self-destructs, destroying the bunker. Having escaped the explosion Osgood and the team were then rescued by the American arm of UNIT. (The Dalek Transaction)

Working late in her lab, on Halloween, Osgood picked up a broadcast from an obsolete satellite called Voxtel, partially broadcasting in Latin. When Josh arrived back from a party saying he saw an apparition of a Grey Man, at the same time as the broadcast, Osgood believed the two were connected in some way. After hearing some unsettling messages from Kate, Josh persuaded Osgood to accompany him up to Ealdon House in a UNIT helicopter. Once there Osgood discovered the apparitions of the Grey Man were created by a particular resonance in the house, causing fear in humans. Alice Donelly had also discovered this resonance in the house years before and she wanted to harness it as a weapon before Kate’s father stopped her. Now with apparitions of the Grey Man appearing across London and an unknown alien presence drawing near, responding to the Voxtel message Alice left years ago, Osgood and Kate deciphered and completed the message, averting the crisis. (Invocation)

After attending the New Science Conference Osgood ran into an old mentorof hers, Professor John Torrance. He persuaded her to let him give her a lift home, or close to, but he ended up taking her to his workplace, the Torrance Research Foundation. There, Osgood discovered Torrence and his colleague Christine Colley had been engaging in cloning research, and was introduced to Max, a cloned Rhesus Macaque. She also discovered a captured Sontaran called Merx who had been experimented on so Torrence could clone a Sontaran army via his own methods. This army would then be sold off through Colley’s contacts in the worldwide auction. Confined together, Osgood and Merx hatch a plan to escape, but they are rescued by a combined force of Sontarans and UNIT. With the cloning project and the Foundation being shut down, Osgood takes Max to safety. (The Sontaran Project)

Osgood and Josh became trapped in a sideways dimension after an experimental travel capsule took them there by mistake. Here UNIT was run by a fascist state with different versions of the team, including herself. She was startled to discover this world’s Osgood and Josh were very much an item, and she had some trouble avoiding his advances. Unfortunately, Josh was forced to leave with the evil Osgood, but the capsule left behind a dimensional tear that non-evil Osgood used as a gateway to jump across to her reality. When she returned, Josh, without thinking, planted a large kiss on her lips before realising his mistake. Soon the other Osgood attempted to escape again in the capsule. With its power levels approaching critical Osgood managed to persuade herother self to jump start the capsule just before the dimensional gateway imploded. Heading to Kate’s office, this left the real Osgood and Josh’s relationship ambiguous. (False Negative)


Osgood went with Kate to find Bishop in an auctioneers base. The Overseer gave her a pairof virtual reality goggles which held instructions for both of them to follow. This lead them to a site outside Bristol. She had to solve puzzles in the virtual world to stop bombs in the real world. She worked out that they didn’t need to race around the UK they needed to be at the Auctioneer’s warehouse. She found Bishop in a box in the centre of London. She thought that the VR technology came from a parallel world. (Game Theory)

On examining the VR equipment she realised it was a bridge to another universe. She, Carter and Shindi experimented in the virtual world. She thought that it was amazing that they could actually interact with the parallel world. In this world they were attacked by mutated dogs and then by metal worms. She observed that the dogs had been converted and realised that the world could be affected by their imagination. She became concerned when they realised they were on a parallel Earth. She thought that there was something familiar about the hive she saw in the virtual world. She started to be cyber-converted. (Telepresence)

She was connected to the cyber-network. She stopped the Cyberman from fully converting Bishop and Shindi. She told the cybermen that was arrogant and that they were using emotional responses and that’s why she wasn’t converted. She tried to workout what they were doing and told them that she could get the whole Earth under control within a matteron minutes. She planned to use the Auctioneer app to use this. She got the Cybermen to find Kate in order for her to reverse the communications blackout. Using her improved hacking skills, she undid Kate’s communications shield and sent the app to everyone on Earth. (Code Silver)

She realised that The Master was in the UNIT base and updated the Cybermen on him as well as getting her gun that might stop him. She asked the Cybermen to convert The Master. She sent Shindi and Bishop after Kate, The Master and Carter. She again had to remind the Cybermen not to convert her again, and she showed them her usefulness by changing a conversion unit to work on a Time Lord. She placed The Master in the conversion chamber. Shortly afterwards she was uncoverted. She was used by The Master as a hostage so that he could escape. She rewrote the app again to uncovert the humans. (Masterof Worlds)


Kate told Osgood to deliver what The Master had found in the Auctioneer’s vault to The Well. She later interviewed Shana Siddiqui for a position. During her time in a decontamination suit she wore a stick of Celery. She asked Shana to help her study a Wirrn. After the Wirrn escaped, she discovered that Shana had been infected and planned to study the infection. She tried to get Shana to resist the infection. She used the Ravens to attack the Wirrn. After discovering that it was an ancient virus that killed the Wirrn, she injected Shana with one from the Archive. (Hosts of the Wirrn)

Whilst undertaking an experiment, she was interrupted firstly by Josh then by a capsule coming to the Tower. She worked on trying to translate the language of the creatures. She later explored the Black Archive for a weapon Vara told her about. She wasn’t happy that Kate was going to hand over the aliens to her people, and thought it wasn’t fair. She supplied Vara with the weapon. (Breach of Trust)

She joined Kate on an investigation to the Pandora Institute. Whilst there she experienced a nightmare where she was useless to stop an invasion. She managed to get back her communications device and contacted Shindi. She later told Josh of this, and they realised that they had both heard the same noise. She worked out that Seth Hyer projected the fears of the patients which made some of them die. She got Shindi to send a platoon to the island as there was an alien incursion. She reconfigured her holograms to reflect Seth’s own image which destroyed it. (Open the Box)


The two Osgoods created Operation Double, where a group of 20 million Zygons would be allowed to live on Earth and take on the form of the nearest person they could find. The treaty could only be maintained if both humans and Zygons agreed to live among each other in peace, and that no harm would come to anyone. They were given a device called the Osgood Box by The Doctor, only to be used only in a dire emergency. (The Zygon Invasion)

In 2014, one of the Osgoods was sent to Bonnybridge to investigate another U.F.O. sighting in the area. Because of this, she missed the first known interaction between the Twelfth Doctor and UNIT as well as the Fractures’ attack on London. (The Fractures)

After her Zygon double was killed by Missy, (Death in Heaven, Narcissus) Osgood refused to state whether she was the Zygon or the human in order to maintain the treaty. She became a target of a revolt from a rogue group of Zygons who believed they had been betrayed. (The Zygon Invasion)

After The Doctor convinced Bonnie, the leader of the Zygon revolt, to stop her plan, Bonnie also assumed Osgood’s form and acted as the second protectorof Earth alongside the other surviving Osgood. She felt that they were a credited it to both humans and Zygons and planned to take on the role of protecting the Earth from threats. (The Zygon Inversion)

In September 2015, the two Osgoods watched prime minister Daniel Claremont’s speech on global warming at Ravenscaur School with Kate Stewart in the Towerof London. After Claremont was revealed to be a Sea Devil during the speech, the Osgoods recommended that Kate call The Doctor. The Twelfth Doctor was already there and he defeated the Sea Devils without UNIT. (Clara Oswald and the School of Death)

Inearly 2016, one of the Osgoods was in London when it was attacked by K2. She called the Twelfth Doctor and he took her into his TARDIS. They materialised above the London Eye as it was attacked by the robot. The Doctor used his sonic screwdriver to destroy K2, but he fell out of the TARDIS. Osgood saved him by throwing her scarf out of the TARDIS for The Doctor to catch. (Robo Rampage)

One Osgood mailed the other based on a large increase of transmitter activity coming from Saxon Heights. They realised that this was Missy and later had UNIT crash into the school. However Osgood later confirmed to Kate Stewart that they had lost her. (Yes, Missy)

One of the Osgoods was the commanding force behind UNIT’s shutting down of Harmony Shoal, following an anonymous tip off. (The Return of Doctor Mysterio)

When UNIT operations became suspended due to funding disputes, all members of the organisation, including the Osgoods, presumably lost their jobs. (Resolution)


Osgood was a”fan ” of the Doctor and knew of many of his previous incarnations. She would pick iconic items (i.e. multi-coloured scarf, bow tie) from the incarnations she knew of and wore them herself. (The Zygon Inversion) When asked by the Twelfth Doctor if she would like to travel with him, she was so excited that she had to use her inhaler. (Death in Heaven) Osgood would become saddened if she learned she missed a chance to see The Doctor, one of her fellow scientists even stated she would be disheartened to learn The Doctor had regenerated again after she had just started mimicking his previous self’s fashion. (The Fractures)

Osgood was also very intelligent. She alone was able to work out the reason why the Zygons smashed the statues in the Under Gallery. (The Day of the Doctor) She also surprised the Twelfth Doctor by correctly presuming that Missy was The Master regenerated into female form: UNIT kept files on all past Prime Ministers, including The Master. (Death in Heaven) She also came up with a hypothetical plan for invading Earth by killing The Doctor by shooting him between the eyes for each regeneration, never allowing him to talk. (The Zygon Inversion)

She managed to figure out whether she or her Zygon doppelganger was the real Osgood after the Tenth and Eleventh Doctors, joined by the War Doctor, jumbled their minds, making them unable to determine their own species, in an attempt to facilitate negotiation of the ultimate peace treaty. She managed to determine this as her Zygon counterpart suffered an asthma attack, motivating her to pass her asthma inhaler to the other Osgood. (The Day of the Doctor)

Osgood had a sister to whom she negatively compared herself. (The Day of the Doctor) Missy observed that she had little confidence in herself. Osgood was able to keep her cool, even when faced with the threat of death from Missy and tried to reason her way out. (Death in Heaven)


Osgood dressed according to The Doctor’s fashion senses from various incarnations, choosing to wear a similar scarf to that worn by the Fourth Doctor. (The Day of the Doctor, Robo Rampage) She later wore trainers similar to those worn by the Tenth Doctor and a bow-tie similar to that worn by the Eleventh Doctor and a leather jacket like the Ninth Doctor. (Death in Heaven) She also wore a shirt with question marks on the collars, like the Fourth, Fifth and Sixth Doctors. When the Nightmare scenario occurred she wore items of clothing similar to the Seventh Doctor when he visited Maiden’s Point. (The Zygon Invasion) On at least one occasion she wore a costume inspired by the Sixth Doctor. (The Lost Dimension) When Kate sent Osgood on a mission with Jo Jones she wore a velvet jacket and a frilly shirt like the Third Doctor. (Tidal Wave)

She had tattoos of the Doctor’s various incarnations across her body, and wanted to add all of their faces eventually. (The Day of the Doctor)


  • On 24 July 2014, Ingrid Oliver appeared in-character as Osgood in a video thanking fans for helping the official Doctor Who Twitter account reach one million followers.
  • In DWM 484, Steven Moffat admitted his intention when writing was for Osgood to be the daughterof UNIT soldier Tom Osgood. However, he did not want to state this definitively in the script so fans would be able to form their own interpretations.
  • In the audio story Power Cell, Osgood responds to the suggestion that she had an uncle who used to run around shooting aliens with “something like that.” This is consistent with the theory that Tom Osgood is Osgood’s father and with the lack of definitive confirmation.
  • In the audio story Call to Arms, John Benton says Osgood is “just like him”, and she automatically assumes he means someone specific other than The Doctor -“you mean, just like my…” – but her enquiry cut short before she names them.
  • Osgood appears as a background character in the London scene and the hidden Black Archives location inThe Doctor Who level pack in LEGO Dimensions.
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