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) focus on the character of Rose Tyler and characters connected to her. For example, although Adam Mitchell was a companion by the standard definition, he appeared in only two episodes and was arguably a less significant part of the 2005 series than Rose's sometime boyfriend Mickey Smith, who was not technically a companion but appeared in five episodes (or six, including a brief appearance as a child in "Father's Day"). Mickey later gained full-fledged companion status when he travelled in the TARDIS in the 2006 episode "School Reunion". In that episode, Sarah Jane Smith referred to Rose as the Doctor's