The Mammoth Book of Extreme Science Fiction is a science fiction anthology edited by Mike Ashley, originally published in 2006 in the United Kingdom by Robinson, an imprint of Constable & Robinson Ltd.

It was reprinted in the United States, also in 2006, by Carroll & Graf, and imprint of Avalon Publishing Group.

It is one of a long series of "Mammoth Book" short story collections edited by Ashley and published by Robinson, most of which have themes outside of science fiction.

The book includes 19 science fiction short stories, along with a two-page introduction entitled "Extreme Science Fiction" by Mike Ashley, on the theme of the anthology.

One author is represented twice in the collection: Jerry Oltion.