13. Captain Jack Harkness
Played by: John Barrowman
First appearance: “The Empty Child” (S01E09)
Companion to Doctors: Ninth and Tenth
Reason for departing: Jack was thought to have died, but after being reunited with the Doctor, he realized that he valued the team he had built in Torchwood and left to rejoin them.
A time-traveller from the 51st Century, Jack Harkness is the first openly bisexual character to appear as the Doctor’s companion, romancing Rose and the Doctor in equal measure. He is brought back to life imprecisely by Rose when she is Bad Wolf enabling him to cheat death constantly and worries over whether he will ever die. It is hinted in “The Last of the Time Lords” (29.13) that he is also the ‘Face of Boe’ who died in “Gridlock” (29.3). Jack has also appeared as the lead in his own spin-off, Torchwood, which is currently in production for its fourth season.
12. Dorothy Gale “Ace” McShane
Played by: Sophie Aldred
First appearance: “Dragonfire” (S24E12)
Companion to Doctors: Seventh
Reason for departing: Ace’s reasons for leaving are unknown. She was still travelling with the Doctor when the Classic series ended but is no longer with him when he regenerates.
It was unfortunate that this companion joined the Doctor at such a low point in the series’ ratings and history because she was very sassy, had a love of explosives, and enjoyed a fatherly relationship with the Doctor, whom she nicknamed the Professor. Ace encountered the Doctor first on the Iceworld, on which she had been deposited thanks to the machinations of Fenric.
Played by: Gerald Flood
First appearance: “The King’s Demons” (S21E21)
Companion to Doctors: Fifth
Reason for departing: Crushed to pieces in the tissue compression eliminator.
Kamelion was an android who could change form. He was initially under the thrall of the Master but the Doctor broke this and took Kamelion aboard the TARDIS. Unfortunately, Kamelion was weak-willed and fell under the Master’s control again, leading him to beg the Doctor to destroy him (which he did).