Rabbit

"What part of ‘I'm not your lunch’ do you not understand? I already gave you the key! Put me down!"

- Rabbit

Rabbits of the Mushroom Kingdom, much like their "Real World" counterparts, are small, furry mammals with long ears and large hind paws. They're common in the fields and wooded regions of the kingdom. These animals also feature quite prominently in several Mario games.

Nintendo Comics System
In the Bowser Knows Best issue of Nintendo Comics System, the Koopa Family has a pet rabbit named Pookie who they often mistreat, but escapes soon after his introduction.

Nintendo Adventure Books
In Leaping Lizards, Morton Koopa Jr. sneaks into the palace, vandalizing it and transforming the Mushroom King into a rabbit with his magic wand. Luigi's attempt to change the king back with the same scepter only makes matters worse, changing the king from a normal bunny into a human-sized one. In a later book, Unjust Desserts, Magikoopa sneaks into the palace garden with some enemies he had shrunk by shapeshifting into a rabbit.

Wario's Woods
In the SNES game Wario's Woods, a suit-wearing rabbit by the name of Harry Hare faces Toad, as the seventeenth boss.

Super Mario 64 DS
In Super Mario 64 DS, rabbits feature much more prominently. They are found throughout the castle grounds (and their locations vary from character to character). The designated rabbits for each character have a specific color - yellow for Yoshi, pink for Mario, green for Luigi, and orange for Wario. If caught, they would unlock mini-games for the player to play in the Rec-Room.

Special Glowing Rabbits needed to be caught to unlock a white door in the Character Door room, behind which was a secret Power Star. They will appear only after collecting at least 50 Power Stars.

Although they did not appear in the original Super Mario 64, there was a single yellow rabbit named MIPS who would run around the basement area and grant Mario a Power Star should he be caught.

'''Yoshi (Yellow Rabbits):
 * 1-3: Outside the castle, at the end of the bridge
 * 4: Outside the castle, in a patch of flowers to the right
 * 5: Outside the castle, at the bottom of the drained moat
 * 6: Outside the castle, to the left among the maze of hedges
 * 7: In the basement, in front of the entrance to Lethal Lava Land
 * 8: At the beginning of the game, Yoshi must find the rabbit with the key, located in the hedge maze

Yellow Rabbit quotes with key:
 * "''Aaaaargh! No, don't eat me! All I did was tease you a little. C'mon, let me go. (spat out) Aiyeeee! I though it was the end for little old me...My entire life flashed before my eyes! Talk about scary! Anyway, here, take the key. It's just slowing me down."
 * "Give me a break. I already gave you the key."

'''Mario (Pink Rabbits):
 * 1: Outside castle, left of the bridge
 * 2: Outside castle, at the bottom of the moat (after it's been drained)
 * 3: Inside the room with the entrance to Jolly Roger Bay
 * 4-5: In the basement, in front of the entrance to Lethal Lava Land
 * 6: On the second floor of the castle, at the very top of the stairs
 * 7: On the second floor of the castle, in the room with the large mirror wall

'''Luigi (Green Rabbits):
 * 1: Outside the castle, to the left among the maze of hedges
 * 2: In the room with the entrance to Bob-Omb Battlefield
 * 3: Behind the castle, in the courtyard with the boos (back flip right outside the doorway)
 * 4: In the basement, in the room where the water can be drained from the moat
 * 5: On the second floor of the castle, just right of the doorway
 * 6: In the room with the entrance to the Goomboss Battle (behind the Rec Room)
 * 7: Outside the castle, on the roof (150 stars needed to unlock the cannon)

'''Wario (Orange Rabbits):
 * 1: Outside the castle, to the far right
 * 2: In the room with the entrance to Whomp's Fortress
 * 3: In the basement, in the left hall with Toad
 * 4: Behind the castle, in the courtyard with the boos
 * 5: On the second floor of the castle, in the halls with the entrance to Tiny-Huge Island
 * 6: On the third floor of the castle, near the entrance to Tick Tock Clock
 * 7: On the third floor of the castle, in the upper alcove to the left

Super Mario 3D World
Rabbits appear again in Super Mario 3D World, where they can again be chased and caught. Larger variations also appear. When they are caught they give prizes like Power-Ups, Coins, Green Stars, or even a Mega Mushroom.