Although his role has not been revealed, the report states that Del Toro - who was last year linked to the part of John Harrison in J.J. Abrams' Star Trek Into Darkness - will appear as "a character that is built to be part of future Marvel films, which means he has signed a deal with options that put him into multiple movies." The obvious choice is of course Thanos, given that the Mad Titan has already been set up as a potential bad guy for The Avengers 2 with his mid-credits appearance in last year's blockbuster - not to mention his many ties with the Guardians of the Galaxy.
Guardians of the Galaxy is set to begin filming this month ahead of a release in August 2014. Del Toro and Gillan are to be joined in the cast by Chris Pratt (Parks and Recreation) as Peter Quill/Star-Lord, Zoe Saldana (Avatar) as Gamora, Dave Bautista (Riddick) as Drax the Destroyer, Michael Rooker (The Walking Dead) as Yondu, John C. Reilly (Step Brothers) as Rhomman Dey and Glenn Close (Damages), while Lee Pace (The Hobbit: An Unexpected Journey) and Ophelia Lovibond (London Boulevard) will portray two further as yet unrevealed villains.