Katarina

Katarina is a servant girl from Troy who is tasked with spying on Vicki when the Doctor and his Companions wind up there during the Trojan War. She befriends Vicki and ends up caring for the injured Steven, helping the Doctor carry him into the TARDIS, which convinces her the Doctor is Zeus. At the end of her first story, Katarina joins the Doctor and Steven aboard the TARDIS, though it will not be for long.