Porcupo

Porcupos are small, spiked creatures found in Super Mario Bros. 2. They are said to be a type of, but more closely resemble a.

Porcupos are one of a few enemy characters from SMB2 that have never gone on to reappear in any subsequent games, though a Porcupo-like character did make an appearance in Mario Kart 64. Super Mario World 2 similarly features a hedgehog enemy called a "Super Porcupo" in Japanese, though in English it's known as Harry Hedgehog.

Super Mario Bros. 2
In their first appearance in Super Mario Bros. 2, they pace back and forth and are usually in groups of two or more. They cannot be jumped on or picked up, so players must throw other enemies or objects at Porcupos to defeat them. Unlike other enemies, Porcupos have a three-frame walking animation, made by moving the front two 8x8 pixel tiles around, thus also using only half as many actual graphics as most other enemies. Their artwork shows them with white faces and red noses, though in game, they have tan faces and gray noses instead, despite how the artwork's colors would be mapped accurately to the game's red palette. Their feet are also colored the same as their body in their original sprites.

Porcupos reappear in the Super Mario Bros. 2 port included in Super Mario All-Stars. They behave exactly the same as in the original, but are purple in color. Likely due to the increase in detail, they now have a two-frame walk animation with separate sprites, like most enemies in the game.

Super Mario Advance 4: Super Mario Bros. 3
Porcupos are also in Super Mario Advance 4: Super Mario Bros. 3, but only in the World-e level, Ground Work. They are recolored a shade of blue.

The Super Mario Bros. Super Show!
A single Porcupo appears in The Super Mario Bros. Super Show! episode "On Her Majesty's Sewer Service" as the pet of Koopfinger. When Mario and Luigi invade Koopfinger's hideout, the Porcupo simply hops off Koopfinger's lap and runs away instead of trying to fight.

Mario Kart 64
Mario Kart 64 features Porcupo-like enemies known simply as porcupines and alternatively called Spinys. They appear in Yoshi Valley, sidling back and forth in the middle of the road in certain paths. If a racer hits a porcupine, their kart will spin out. In the Mario Kart 8 rendition of the course, the porcupines have been replaced with Goombas.