William Olaf Stapledon (10 May 1886 – 6 September 1950) was an English philosopher and author of science fiction. His visionary approach to science fiction, with an emphasis on cosmic evolution, philosophical inquiry, and the future of humanity, has left a lasting legacy in the genre. In 2014, he was inducted into the Science Fiction and Fantasy Hall of Fame.

Stapledon's writings directly influenced well-known authors such as Arthur C. Clarke, Brian Aldiss, Stanisław Lem, C. S. Lewis, and John Maynard Smith, contributing many ideas to the world of science fiction.