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) "assistant", a term to which the latter took offence. This exchange might be regarded as indicating the new series' shift in approach to the companion role. Adam was also far less significant than Rose's mother, Jackie Tyler, who was a frequently recurring character who travelled in the TARDIS, yet is not considered a companion. As of the end of the sixth series, Sarah Jane Smith is the only classic era companion to have travelled again with the Doctor in the revived "series", and one of two to have done so in the revived "era". She declined his invitation in "School