Sean Christopher McMullen (born 21 December 1948 in Sale, Victoria) is an Australian science fiction and fantasy author.

McMullen is one of Australia's leading science-fiction and fantasy authors and has written over 70 stories and 17 books.

His first novel was originally published in Australia as two separate books, Voices in the Light (1994) and Mirrorsun Rising (1995).

After this book's success, his first two novels were rewritten and combined for a publication in the US as Souls in the Great Machine (1999), which, in turn, became the first volume of the Greatwinter trilogy, a unique mix of the generally anti-genres steampunk and cyberpunk.

McMullen has recently retired from a career in scientific computing to concentrate on his literary work.