Mega Unagi

Mega Unagis are a gigantic versions of the Unagi that appear in New Super Mario Bros. Mega Unagis chase Mario (or Luigi) through two underwater stages in the game, 4-3 and 8-3, trying to eat him. They are very dangerous, and eat everything they can, such as Brick Blocks and ? Blocks. There is no way to defeat a Mega Unagi. However, Mario can go "through" one with a Mega Mushroom or a Starman, by swimming through its back, as Mario will collide with it if he tries to go through its face. Unlike Cheep Chomps, Mega Unagis can't actually eat Mario and cause him to lose a life instantly, instead the player will take damage like a regular enemy.

In Mario Kart Wii, Mega Unagis appear in the Chain Chomp Wheel battle course and in Koopa Cape as freely-swimming eels that swim under the tunnel, unlike their smaller relatives in the same course, who are seen as living in pipes.

A single Mega Unagi appears on the Mario Kart 8 track Dolphin Shoals at a portion of track inside a cave, where players race along its body for a short section. It returns in Mario Kart 8 Deluxe.