Salvo the Slime

Salvo the Slime is the boss of World One in the game Super Mario World 2: Yoshi's Island. Salvo jumps at you but is completely harmless. The only problem is the smaller slimes that break off when you egg him and the lava pit. Toss eggs at him enough times and you'll win.

Salvo makes a surprise reappearance in Bowser's Castle at the end of World 6, carrying a key. Two of them also appear in Red nosed the Tap Tap's fort. At these points, Salvo no longer sheds smaller slimes when hit.

Salvo makes an unexpected appearance as the boss on the second floor of the duel tower in Mario Party Advance, surprisingly this game shows he is capable of speech.

Various Big Slimes appear in Mario Party 4's Slime Time. They come in many different colors.

Trivia

 * Gilbert the Gooey was probably inspired by Salvo.