Thrice Upon A Time is a science fiction novel by British writer James P. Hogan, first published in 1980. Unlike most other time travel stories, Thrice Upon A Time considers the ramifications of sending messages into the past and/or receiving messages from the future, rather than the sending of physical objects through time.

James Patrick Hogan was a British science fiction author. His major works include the Giants series of five novels published between 1977 and 2005.