A pet was a creature kept by a sentient being for companionship. Common human pets included cats and dogs. (PROSE: Mrs Acres)
At a point where most of the planet Mondas had not been converted into Cybermen, Cybermats were kept as pets by the native Mondasians. (AUDIO: Spare Parts)
Jarra To hypothesised that the Doctor kept companions around the TARDIS as pets. (AUDIO: The Axis of Insanity) Missy agreed with this perspective, believing that only other Time Lords could qualify as the Doctor's true friends. (TV: The Magician's Apprentice)
The Eleventh Doctor claimed that he did not keep pets, but made friends. (COMIC: After Life) The TARDIS herself regarded his companions as "strays" he kept bringing home. (TV: The Doctor's Wife)
Helen A had a pet Stigorax named Fifi. (TV: The Happiness Patrol)
Introducing Rose Tyler to her force-grown clone servant Chip, the Lady Cassandra referred to him as her pet. (TV: New Earth)
In Pete's World, Pete and Jackie Tyler had a pet dog named Rose, which was the name of their counterparts' daughter in N-Space. (TV: Rise of the Cybermen) In another reality, they had a cat named Rose. (AUDIO: The Endless Night) Following Rose Tyler being trapped in Pete's World, the Tenth Doctor adopted his own cat named Rose. (COMIC: A Rose by Any Other Name)
Myfanwy was Torchwood Three's pet pterodactyl. (TV: Cyberwoman)
After running away from the Spacefleet Academy, Bernice Summerfield kept two pet turtles, Speckley and Squidgy. (AUDIO: The Shadow of the Scourge)
In the Vault of the New Dalek Empire's Crucible, the Tenth Doctor mockingly proclaimed that Davros was the Daleks' pet. (TV: Journey's End)
The Master did not allow their daughter to keep pets. (PROSE: The Liar, the Glitch and the War Zone) When on Skaro during their Missy incarnation, the Master took a Slyther as a pet, naming it Doctor. (PROSE: Postcards from the Universe)
When the Thirteenth Doctor summoned Death Squad Daleks to Earth to destroy the Defence Drone Daleks, she mocked that the former had come like "obedient little pets", an insult that enraged the Daleks into falling into the Doctor's trap. (TV: Revolution of the Daleks)