Jumbo Jellyfish (ジャンボくらげ) is the fourth boss from Alex Kidd: The Lost Stars.
Jumbo Jellyfish appears as a giant jellyfish. It appears twice during the stage, at the middle portion and at the end of the stage. In the Arcade version of the game they appear in groups of three, swimming around and moving their tentacles below. In the SMS version they appear in pairs and are immobile, serving as huge obstacles, moving their giant tentacles below themselves and releasing smaller jellyfish which pursue the player.