Rabbit

A rabbit was a small Earth mammal.

Rabbits on Earth
On Earth, rabbits were so prized for their meat that they could inspire poaching. This certainly happened in England around the time of the Great Fire of London. (TV: The Visitation) Centuries later, Ernie Clements, the poacher who worked the grounds of Marcus Scarman's house, caught a rabbit shortly before spotting a robot mummy removing itself from one of his traps. (TV: Pyramids of Mars) Rabbits were also kept as pets. The Fifth Doctor, Nyssa and Tegan Jovanka once met a boy named Rithros who had lost his pet rabbit. The Doctor used his celery stick to lure the animal back to his master. (PROSE: Goths and Robbers)

Charley Pollard had a pet rabbit named Mopsy. (AUDIO: Zagreus)

Magicians used to pull rabbits out of hats. (TV: The Sontaran Stratagem, COMIC: The Hat Trick)

Boa constrictors preyed on rabbits and ate them whole. (TV: The Time Monster)

The Tenth Doctor came across a rabbit in Elizabethan England and, believing it to be a Zygon in disguise, gave it an intimidating speech only to realise it was just an ordinary rabbit, amending it to a "general warning". (TV: The Day of the Doctor)

As slang
The Fourth Doctor once asked K9 if he wanted to chase some rabbits. Adric had to explain to him that this meant they were going somewhere. (PROSE: Inter-Galactic Cat)

"Rabbits!" was a favourite interjection of Tegan Jovanka. (TV: Logopolis, PROSE: Graham Dilley Saves the World) The Eleventh Doctor once used the word in a similar way. (COMIC: Hunters of the Burning Stone)

Extra-terrestrial rabbits
The Eighth Doctor and C'rizz once encountered some rather large rabbits on Caerdroia. At the time, the Doctor told C'rizz that there were rabbits on Gallifrey, as well, but they were "rounder and cuddlier" than Earth rabbits. (AUDIO: Caerdroia)

According to the Third Doctor, a giant rabbit was a delegate at the Third Intergalactic Peace Conference. (TV: Frontier in Space)

On Dagomere, giant rabbits were known to dig large tunnels. (PROSE: The Tree of Life)

While trapped in an Alice in Wonderland-inspired reality, one of the characters encountered by Peri Brown was a version of the story's White Rabbit who strongly resembled the Sixth Doctor. (COMIC: Salad Daze)

A young Gallifreyan child was holding a stuffed rabbit toy during the Fall of Arcadia. (TV: The Day of the Doctor)