If you’re a fan of new “Who” and Susan’s name doesn’t ring a bell, that’s because she appeared in the earliest episodes of the original series, acting as one of the companions to the First Doctor (William Hartnell) from 1963 to 1964. Susan (Carole Ann Ford) was the Doctor’s granddaughter and seemed to have lived with him on Gallifrey before coming to earth. The pair live in London in the show’s first season, but when two of Susan’s teachers become suspicious of her otherworldly knowledge, they end up in the TARDIS alongside her, and the Doctor takes all three of them on galaxy-spanning adventures.

Ford wanted to leave the show by its second season because, as she told the Daily Mail, “My character was going nowhere. In truth, I wished I had never gone into it.” By that point, the first season had already aired an incredible 42 episodes, surely a demanding production schedule for any actor. Writers crafted a storyline in which Susan fell in love with a freedom fighter named David in a future, Dalek-occupied version of London. The Doctor left her to build a life with the man she loved, but said he’d return to her one day. The only time Susan has appeared on screen in the main show since was in the 1983 special “The Five Doctors,” when she’s pulled by a Time Scoop that reunites her with her grandpa, as well as future iterations of the Doctor.