"I am Groot." (Translation: Guardians of the Galaxy writer and director James Gunn sometimes prints Groot's scripted dialogue so those who don't speak Groot can understand the tree-like alien.) As Rocket Raccoon (voice of Bradley Cooper) explains to Star-Lord (Chris Pratt) in the first Guardians of the Galaxy: "His vocabulistics is limited to 'I' and 'am' and 'Groot.' Exclusively, in that order." In the Marvel Studios franchise, Groot (voice of Vin Diesel) speaks in three words: "I am Groot," or on one special occasion, "We are Groot." But to those who can understand what Groot is saying, the character communicates like any other.