Whale

A Whale is a large marine mammal mostly found on Earth, but first appeared in the Mario game Super Mario Bros. 2.

Super Mario Bros. 2
Whales appeared in level 4-2 of Super Mario Bros. 2. Players can hop on their backs and gain elevation by standing on their blow holes as water sprays out. The water will hurt the player if they touch it from either side but a Star can be used to destroy the spout. Pink (blue in remakes) Snifits and Shy Guys patrol the backs of some whales. There is also one whale which has grass growing on its back.

Super Mario Land 2: 6 Golden Coins
In Super Mario Land 2: 6 Golden Coins, Mario has to go inside a whale and travel to the whale's end in order to defeat the Octopus boss.

Wario Land: Super Mario Land 3
In Wario Land: Super Mario Land 3, one of the treasures Wario collects is a whale-shaped collectible.

Paper Mario
An individual Whale appeared as a character in Paper Mario, where he aided Mario and his allies by getting them across the sea to Lavalava Island.

WarioWare, Inc.: Mega Microgame$!
The Whales from Super Mario Bros. 2 also appear in WarioWare, Inc.: Mega Microgame$! in one microgame.

Wario: Master of Disguise
In Wario: Master of Disguise, a species of cyborg whale called Cyborca appeared as enemies in the game.

Donkey Kong Country Returns
In Donkey Kong Country Returns and Donkey Kong Country Returns 3D, the level Blowhole Bound features whales that Donkey Kong and Diddy Kong can ride on. After freeing a whale from an anchor, the Kongs can ride on its back to cross the water along the shore of the islands. The whales are not very steady and often tilt along the water, allowing the primates to grab some collectibles hidden high in the air. The aquatic creatures sometimes head underwater as well, where the Kongs cannot swim, so the heroes have no choice but to use floating ship parts to progress. These ship parts are often destroyed by the fast-moving whales, so the Kongs have to travel across them quickly. By hand-slapping the whales' blowhole, the Kongs can force the whale to send water out that they can use to reach pickups in higher areas.

The Super Mario Bros. Super Show!
A Whale briefly appeared towards the end of The Super Mario Bros. Super Show! episode "Mario of the Deep". Here, the Whale was rode on by King Neptune, who was using it to body slam his temple, which Barra-Koopa had taken over, along with the rest of Aqua Land. After slamming into the wall several times, the Whale caused a piece of it to shatter away, which Mario, Luigi, Princess Toadstool and Toad were able to pass through. This Whale appeared to be a Blue Whale rather than the variety of Whale from Super Mario Bros. 2.

Nintendo Monopoly
A Whale makes a cameo in Nintendo Monopoly.