A fandub is a fan-made dub or redub of a live-action or animated production. Dubbing is the act of re-recording of a live-action or animated production, typically in a language other than the original. Most productions are translated from different languages, but some fandubs are for productions that were produced in the fandubber's native language. The dialogue can range from being a close translation to a completely-altered version of the original script's story and plots, as well as the personalities of protagonists.

The reasons behind fandubbing can range from the production not receiving an official dub to the official dub being poorly received. Fandubs are most commonly done with Japanese animation, but sometimes include live-action and animated series and movies in any language. Versions where the story line, character personalities, and content are dramatically altered, typically in a humorous manner, are called "Abridged Series" and "fundubs".

Because fandubs typically use copyrighted material, fandubs face the same copyright implications as fansubs but on a different scale. To avoid copyright issues, fandubs are sometimes made using web-based dubbing tools like Dubroo, which does not alter the original videos but just plays the dubbed audio along with the original muted video.

Fandubbing can also refer to a translated cover of a song in another language, frequently anime theme songs. Several English-language voice actors, such as Amanda Lee and Cristina Vee, have published fandub covers on YouTube.