We won't be seeing him fully stretch his evil muscles until his role as the main antagonist in the third "The Avengers" film in 2018. However, this coming August, we might just be hearing the voice of the alien menace Thanos for the first time.
Latino Review reports that whilst we have glimpsed the purple-skinned villain for all of a few seconds at the end of "Marvel's The Avengers," they have learned that James Gunn's upcoming "Guardians of the Galaxy" includes a scene in its third act with Thanos on a "rocket throne".
It has been suggested the appearance is long enough that someone is going to have to provide the voice of the Mad Titan. According to their sources, that person will be Josh Brolin. From the sounds of it the performance will be voice only, not motion capture as well.
Deadline followed the report up, not only confirming Brolin's casting but saying it actually happened months ago and Brolin has already completed all his voiceover work.