Professional bodybuilder, author, entrepreneur, and philosopher. He published numerous fitness-themed books, including Heavy Duty Nutrition and High-Intensity Training the Mike Mentzer Way.
He began his bodybuilding career after winning the Mr. Universe title in 1978.
He was a follower of author Ayn Rand's philosophy of Objectivism: he believed that mind and body are one and the same.
He was the brother of fellow bodybuilder Ray Mentzer. A native of Germantown, Pennsylvania, he died of heart failure in Rolling Hills, California at the age of forty-nine.
He was defeated by Arnold Schwarzenegger in the 1980 Mr. Olympia bodybuilding competition.