The role first appeared at the end of 'The Avengers'.
The film, set for release on August 1, stars Chris Pratt as Peter Quill, the leader of the misfit Guardians.
Zoe Saldana, Dave Bautista, Vin Diesel, Bradley Cooper and Lee Pace also star in the film, being directed by James Gunn from a screenplay by Gunn and Nicole Perlman, said the Hollywood Reporter.
Thanos is a purple-hued alien who is considered one of the most dangerous Marvel villains of all time, and is part of a group of god-like beings called The Eternalsand.