Monster Party is a 1989 action platformer for the NES developed by Human Entertainment and published by Bandai.
The game is about a boy named Mark who is recruited by a winged beast named Bert to fight monsters on Bert's home planet. Bert fuses with Mark, and throughout the game, Mark is able to transform into Bert at various times by consuming a large white and red pill. Mark is armed with a baseball bat which he uses to beat enemies to death or to hit projectiles back at them.
The game features eight levels and one final boss encounter which can each be accessed from the main menu through a password system. The game also features a multitude of bizarre bosses and enemies including fried shrimp, talking plants, and a dancing zombie duo. The game is well known for these bizarre creatures and its overall quirky sense of humor.
The game was set to be released in Japan with the title "Parody World Monster Party", so named for the many horror movie/TV spoofs it contains. The game was canceled before it could be published, though it eventually made its way to the US. Prototype carts of the Japanese version have recently started to appear.