Salvo the Slime

Salvo the Slime is the boss of World 1 in Super Mario World 2: Yoshi's Island and its remake. Salvo is a Slime Drop that was enlarged into by Kamek. Salvo jumps at the player, trying to push them into a lava pit below his arena, though unlike most enemies, the player is not hurt by Salvo's touch. Instead, Yoshi is hurt by the Slime Drops that Salvo summons. Because Salvo was a Slime Drop prior to his transformation, Slime Drops break off of Salvo when he is hit by an egg. The more Salvo is hit, the smaller he gets, until he disappears altogether.

An alternate variant of him appears later as a non-boss enemy in the game, known in English simply as Slime. It can disguise itself as a block, and is defeated the same way. Slimes appear again in Yoshi's New Island.

Four different Salvo the Slimes appears in Mario Party 4 under his Japanese name, Big Slime. During the minigame Slime Time, the four versions of him appear, in yellow, pink, purple, and green.

Going only by his first name, Salvo makes an appearance as the boss of the second floor of the Duel Tower in Mario Party Advance. This game shows that he is capable of speech. Salvo challenges the player to a game of Volleybomb and rewards the player with the minigame upon defeat.

He also makes a brief cameo alongside other Super Mario World 2: Yoshi's Island bosses in the opening to Yoshi's Island DS.

Trivia

 * Although Salvo is indeed a name (actually a surname), its use in this character's name is a pun on "saliva," referencing his slimy texture. It may also refer to how it discharges multiple Slime Drops (i.e. a "salvo") when hit by an egg.