Vin Diesel plays Groot in 'Guardians of the Galaxy' LOS ANGELES, Dec. 22 (UPI) -- Marvel Studios says actor Vin Diesel has been cast as Groot, a sort of giant tree, in the upcoming film "Guardians of the Galaxy." The studio's confirmation came after Diesel posted a photo that showed him hugging a model of Groot, the Hollywood Reporter said Saturday. Diesel has been hinting at the role for some time, posting photos that showed him with motion-capture equipment. The movie's director, James Gunn, reposted the photo on WhoSay with words of praise for the actor: "Vin Diesel is a super awesome dude. I can't tell you how much I like this guy. The movie is currently scheduled for release Aug. 1, 2014, in the United States. The cast includes Chris Pratt, Zoe Saldana, Bradley Cooper, Benicio del Toro, John C. Reilly and Glenn Close.