Ack-Ack Macaque is a 2012 science fiction novel by English writer Gareth L. Powell.

Ack-Ack Macaque is based on Powell's earlier short story of the same name, which won the Interzone reader's poll in 2007.

The novel has aspects of alternative history as in this version of reality the United Kingdom and France merged in the 1950s to form the nation of Brittany.

The macaque of the title is the star of a highly regarded, exclusive massively multiplayer online role-playing game (with the roguelike feature of character death being final) which is itself set in an alternate reality World War II.

The main character in the novel is former journalist Victoria Valois, who attempts to track down the man who murdered her husband and stole her neural implant while the heir to the throne of Brittany becomes a fugitive after breaking into a Parisian research laboratory.