Harley's Humongous Adventure (Japanese: 化学者ハリーの波乱万丈, Hepburn: Kagakusha Harley no Haran Banjou (Chemist Harley's Stormy Life)) is a side-scrolling 2D platform video game released in 1993 for the Super Nintendo Entertainment System. It was originally developed by Visual Concepts, and funded by publisher Electronic Arts, but eventually published by Hi Tech Expressions.

The player controls Harley, a man in a green suit who has shrunk himself to the size of a bar of soap. Harley's mission is to gather the parts of his shrinking machine to return himself to normal size. Harley advances through the levels, picking up items such as tacks, rubberbands, and marbles. Harley adventures through his lab, where the initial incident occurs, his kitchen, his toy room, where the player pilots a toy tank by himself, his bathroom, and other stages.

Enemies include flies, bees, and ants. Players must avoid such enemy attacks as the flies vomiting overhead. The main boss is a deformed rat that tries to jump on Harley, and after each encounter utilizes a household item for the limb he had lost in the previous encounter.