Babe

Babe is a pig who was kidnapped and genetically modified by the Slitheen into a humanoid form with an advanced brain. Once the Slitheen's spaceship was destroyed in a crash landing, the pig was found by Sharaz Jek, who named him Babe and raised him like a pet.

In the seventh episode of Season 12, the Doctors and company arrive at Sharaz Jek's base on Androzani Minor so they can find him in hopes that he can help them save Weblus from the Cybermen. Babe is discovered by the Ninth Doctor and runs around in panic, until Sharaz Jek shows up and calms him down by tickling him behind his left ear.

In the Season 12 finale, Babe manages to open a set of crates containing robotic Yetis to combat the Cybermen. He tries to escape, only for a Cyber-Leader to shoot and kill him, much to Sharaz Jek's anger.