In the Marvel Comics mythology, Edwin Jarvis was a butler to Tony Stark, not unlike Alfred to Bruce Wayne over at the Distinguished Competition.  For the 2008 film, though, director Jon Favreau opted to make Jarvis an artificial intelligence program designed by Stark and with which he could verbally spar not just at home, but also whilst wearing his armor.

Now J.A.R.V.I.S. will make his third cinematic appearance, as Bettany confirms to LFPress, "This is pretty much the way it always goes. I never get the call until literally about a month or two before the movie comes out, and then they bring me in once everything else is done. I'm literally the last person hired. It's exactly like voicing animation, except I don't even have to sync to anything. It's the easiest gig in the world."

Presumably, the character will also be involved in Iron Man 3, the sequel set to be the first Marvel movie after The Avengers.  Though Favreau is not returning, Kiss Kiss Bang Bang writer and director Shane Black is taking over, with Robert Downey Jr. again sporting that Tony Stark facial hair.  That one is scheduled for May, 2013.

The Avengers, meanwhile, is just over five months away, with a May 4, 2012 release date.  Bettany (well, his voice) joins a cast that includes other Marvel veterans Downey Jr., Chris Evans, Chris Hemsworth, Scarlett Johansson, Tom Hiddleston, Samuel L. Jackson, Stellan Skarsgard, and Clark Gregg.  Newcomers include Mark Ruffalo, Jeremy Renner, and Cobie Smulders.