SF Masterworks is a series of science fiction novel reprints published by UK-based company Orion Publishing Group, a subsidiary of Hachette UK. The series is intended for the United Kingdom and Australian markets, but many editions are distributed to the United States and Canada by Hachette Book Group. As of June 2022, there are 188 unique titles in the series, 186 of which have been printed in the relaunched series. Approximately 230 volumes, including hardcover and revised editions, have been published in total.

Superseding the earlier series Gollancz Classic SF (1986–1987) and VGSF Classics (1988–1990), the SF Masterworks series began publication in 1999. Developed to feature important and out of print science fiction novels, the selections were described by science fiction author Iain M. Banks as "amazing" and "genuinely the best novels from sixty years of SF". Many of the selections had been out of print in the United Kingdom for many years.

Its companion series include Fantasy Masterworks and Gateway Essentials.