Mark Hatmaker is the author of Boxing Mastery, No Holds Barred Fighting: The Clinch and Boxing Mastery, No Holds Barred Fighting: Savage Strikes, No Holds Barred Fighting: Takedowns, and More No Holds Barred Fighting: Killer Submissions. He is the founder of Extreme Self Protection, a research body that compiles, analyzes, and teaches unarmed combat methods. He lives in Knoxville, Tennessee.