Douglas Garrett Marshall is an American mixed martial artist who currently competes as a middleweight. He is a former WEC World Light Heavyweight Champion.

Marshall began his career in the WEC at heavyweight, but dropped down a weight class when ZUFFA eliminated that division upon purchasing the organization. He won the light heavyweight title by defeating Lodune Sincaid and subsequently defended it twice against Justin McElfresh and Ariel Gandulla. After losing his title to Brian Stann, Marshall left the WEC and began competing for the now-defunct Palace Fighting Championships. Under their banner, Marshall fought three times winning all three. He made his middleweight debut against Rafael del Real whom he defeated by TKO.

When TPF Middleweight Champion David Loiseau pulled out of a TPF 10 fight with Giva Santana due to an undisclosed injury requiring surgery, Marshall stepped in to face Santana in a middleweight non-title bout. He lost via technical submission in the first round. Marshall next competed on India's Super Fight League'scthird event, SFL 3, against Zelg Galesic, losing the fight via KO early in the first round.

On November 30, 2012, Marshall made his debut for Bellator. He faced former ICON Sport Middleweight Champion Kala Hose at Bellator 82 winning the fight via knockout at just 22 seconds in the first round. In January 2013, Bellator announced Marshall as a competitor in their inaugural middleweight tournament. His quarterfinal fight took place at Bellator 89 against Andreas Spang. He won the fight via knockout in the first round, advancing to the semi finals against Sultan Aliev. Marshall won the fight by Split Decision.