The Year's Best Science Fiction: Twenty-Fifth Annual Collection is a science fiction anthology edited by Gardner Dozois that was published on July 8, 2008. It is the 25th in The Year's Best Science Fiction series and won the Locus Award for best anthology. The UK edition is entitled The Mammoth Book Of Best New SF 21, the "21st Annual Collection" (ISBN 978-1845298289) and contains the same stories listed.