Season 1 (Series 14) Episode 7: "The Legend of Ruby Sunday" (spoilers)
Well that was a blast from the past...
Following a fakeout where it's theorized that the mysterious woman popping up in episode after episode may be the long lost Susan Foreman (last seen in the episode "The Five Doctors" in 1983), it turns out they were the villain Sutekh, last seen in the episode "Pyramids of Mars" in 1975.
Or, it could be Susan. They know about the Tardis, and theyâve been pretty passive about interactions with the doctor or Ruby. And unlike a lot of people on other forums, not making tea is not necessarily evil. Itâs rude, but itâs not evil.