John Michael Scalzi II (born May 10, 1969) is a renowned American science fiction author and former president of the Science Fiction and Fantasy Writers of America. Scalzi is best known for his Old Man's War series, three novels of which have been nominated for the Hugo Award. He is also famous for his blog Whatever, which he has been writing since 1998 on a variety of subjects. Scalzi won the Hugo Award for Best Fan Writer in 2008 primarily due to this blog, which he has also used for numerous charity drives.

His novel Redshirts won the 2013 Hugo Award for Best Novel. Beyond fiction, Scalzi has penned numerous non-fiction books and columns covering topics such as finance, video games, films, astronomy, writing, and politics. In addition, he served as a creative consultant for the TV series Stargate Universe.