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) Agyeman, Piper, Barrowman, and Elisabeth Sladen title billing for each of their reappearances. Noel Clarke reprised his role in the Series Four finale; although listed as a companion alongside the other actors on the BBC Doctor Who website, Clarke is not credited in this way. In "The End of Time" John Simm receives title billing for his antagonist role as the Master, ahead of Bernard Cribbins as companion Wilfred Mott. Companions in the new series also have a more flexible tenure than their classical predecessors. Several companion characters have returned to the series after leaving the Doctor's company, most notably