Robert Harper is an American personal trainer, reality television personality, and writer. He appeared on the American television series The Biggest Loser, a show he later hosted. He was an advisor on The New Celebrity Apprentice.

CrossFit is a branded fitness regimen that involves constantly varied functional movements performed at high intensity. The method was developed by Greg Glassman, who founded CrossFit with Lauren Jenai in 2000, with CrossFit its registered trademark. The company forms what has been described as the biggest fitness chain in the world, with around 12,000 affiliated gyms in over 150 countries as of 2022, under half of which are located in the United States.