The Yeti (nicknamed Sonic Yeti by production crew) is a giant monster that appears in the film. It is summoned by Sex Bob-omb via a distortion pedal, during the music battle against the Katayanagi Twins. The Yeti is quite powerful and easily destroyed the Twins' Snow Dragons (as well as the Twins themselves). The creature has green eyes to represent Scott's jealousy upon seeing Gideon Graves and Ramona Flowers together.
In the Game
The Yeti also appears in Scott Pilgrim vs. the World: The Game. If all players use their taunts in multiplayer, they'll start a band attack and summon the Yeti, dealing massive damage to all enemies and costing all players 25 guts points or health points if a player has no gut points.