Tracy Louise Ward
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Katz was a Karfelon rebel. She and Sezon helped the Sixth Doctor defeat the Borad.
Her grandfather had met the Third Doctor during an earlier adventure on Karfel at that time, Katz’ grandfather was given a locket with a picture of Jo Grant in it, which was later handed down to Katz. She used the locket to ascertain that Peri Brown was not lying about arriving with The Doctor in the TARDIS. (Timelash)