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) loses old ones. Sometimes they return home, and sometimes they find new causes—or loves—on worlds they have visited. A few companions have died during their travels with the Doctor. Most companions travel in the TARDIS with the Doctor for more than one adventure. Sometimes a guest character takes a role in the story similar to that of a companion, such as photographer Isobel Watkins, who plays a significant role in "The Invasion" (1968), or Lynda in "Bad Wolf" and "The Parting of the Ways" (2005). In the revived era, some guest characters have gained companion status such as Mickey Smith,