Ganatus was a member of the Thal expedition which Temmosus led to the Dalek City in search of food. His brother was Antodus.
After the First Doctor and Ian Chesterton convinced the Thals of the need to fight for their survival, Ganatus, along with his brother Antodus, Kristas and Elyon agreed to accompany Ian and Barbara Wright on their expedition to seek another way into the city via the Daleks’ water supply system. During this experience, Ganatus was impressed by Barbara’s tenacity and courage and even became enamoured of her.
After his brother sacrificed himself to save Ian, Ganatus became depressed, saying there was no point in going on. However, Ian found a way into the city. After making it to the control room, the Thals knocked out the Daleks’ source of power, defeating them.
Ganatus was present to bid The Doctor and his companions farewell, giving Barbara some cloth to make a dress. Ganatus expressed his wish that she could model the finished dress for him, a not-too-subtle hint that he wished her to stay. Barbara was, herself, reluctant to leave Skaro, but still departed in the TARDIS, leaving Ganatus to work with his people in rebuilding their world. (The Daleks)
Barbara never forgot him, and one of the names she and Ian later conferred on their son John was “Ganatus”. (Byzantium!)
In contrast to Temmosus and Alydon, Ganatus doubted that the Daleks would be willing to help his people. Noting how his people had once been fierce warriors and were now peaceful farmers, he wondered aloud if the race they had once known as philosophers, teachers, and scientists might now be the bloodthirsty killers. (The Daleks)