Kid A Mnesia is a reissue compiling the albums Kid A (2000) and Amnesiac (2001) by the English rock band Radiohead. It also includes a bonus disc, Kid Amnesiae, comprising previously unreleased material. It was released on 5 November 2021 on XL Recordings.

Kid A Mnesia was promoted with a campaign on the social network TikTok, followed by singles and music videos for the previously unreleased tracks "If You Say the Word" and "Follow Me Around". It was released to acclaim, though reaction to the bonus material was mixed. It entered the top 10 of several national album charts and topped the UK Independent Albums Chart and the US Billboard Top Alternative Albums and Top Rock Albums charts.

Kid A Mnesia Exhibition, an interactive experience with music and artwork from the albums, was released in the same month for PlayStation 5, macOS and Windows.