Companion (Doctor Who) "Face the Raven", but in a subsequent episode ("Hell Bent") her time stream is frozen at the moment of death by the Time Lords so that they can interrogate her about the Hybrid; the Doctor takes advantage of this to save her life, but she remains technically neither alive nor dead, does not age or have a pulse. After her departure as a companion of the Twelfth Doctor, she teams with the immortal Ashildr and travels in a stolen TARDIS. Other companions died in alternate timelines or alternate lives. "Brigade Leader" Alistair Lethbridge-Stewart, "Section Leader" Liz Shaw, and "Platoon Leader"
Companion (Doctor Who) in the Series Four finale "The Stolen Earth" / "Journey's End" (2008), which features a record eight past, present and future companions: Donna is joined by a returning Rose, Martha, Jack, Sarah Jane, and Mickey, while past companion K9 and future companion Wilfred Mott make appearances. This tendency, plus the increase in "one-off" companions like Astrid Peth and Jackson Lake, has further obscured the matter of who is and is not a companion. The Doctor's companions have assumed a variety of roles—involuntary passengers, assistants (particularly Liz Shaw), friends, and fellow adventurers; and, of course, he regularly gains new companions and