Steven Robert Comisar (born December 30, 1961) is an American criminal and book author. He has been convicted of fraud and extortion multiple times. He used confidence tricks and other techniques to fool his victims. Comisar was in federal prison and was released April 27, 2018.

Comisar grew up in Beverly Hills, California. As a young man he sold a "solar powered clothes dryer" in national magazines for $49.95. Buyers received a length of clothesline. Comisar has been arrested and convicted of numerous crimes. Comisar was convicted of a variety of frauds in 1983, 1990, 1994 and 1999. All these trials took place in Federal court in Los Angeles. In 1999, Comisar was arrested for swindling investors in a fake television quiz show involving Joe Namath. He was sentenced to thirty-three months in jail.

Comisar used the working name Brett Champion during the period when he said he had retired from his criminal activity and posed as a fraud prevention expert and consultant, using it on Dateline NBC, The View, Sally Leeza Crook & Chase and in various other television appearances, and when he wrote the book America's Guide to Fraud Prevention. Comisar is now prohibited from using this alias or from referring to himself as a consumer fraud expert. His book is considered a "piece of fraud history" by the Association of Certified Fraud Examiners and is on display in their fraud museum.