Dragon

Dragons are a race of mythological reptiles in the real world; they have appeared numerous times throughout the Mario series as either enemies, bosses, allies, or gameplay elements.

The Adventures of Super Mario Bros. 3
In The Adventures of Super Mario Bros. 3 in the episode "7 Continents for 7 Koopas", after Bully Koopa painted graffiti all over the Great Wall of China, Mario appears, snatches Bully's wand, and turns the Great Wall into a dragon, which chases after Bully.

Trivia

 * Yoshi, a dinosaur, has been known to transform into a winged, fire-breathing creature known as the "Super Dragon" in Super Smash Bros. Brawl.