Cartoon physics is a jocular system of laws of physics that supersedes the normal laws, used in animation for humorous effect. Normal physical laws are referential (i.e., objective, invariant), but cartoon physics are preferential (i.e., subjective, varying).

Many of the most famous American animated films, particularly those from Warner Bros. and MGM studios, unconsciously developed a relatively consistent set of such "laws" that have become regularly applied in comic animation. For example, when a cartoon character runs off a cliff, gravity has no effect until the character notices and reacts.

In words attributed to Art Babbitt, an animator with the Walt Disney Studios: "Animation follows the laws of physics — unless it is funnier otherwise."

Specific reference to cartoon physics extends back at least to June 1980, when an article "O'Donnell's Laws of Cartoon Motion" appeared in Esquire. A version printed in 1994 by the IEEE in a journal for engineers helped spread the word among the technical crowd, which has expanded and refined the idea. These laws are outlined on dozens of websites.