There's someone who has been in four Marvel superhero films whose name fans see in the credits but whose face has not been seen on the screen. He is someone whose voice was present in the "Iron-Man" trilogy and "The Avengers." The guy is none other than Paul Bettany.

Many may not know that Bettany had the easiest role in the previous Marvel Cinematic Universe movies. He did the voice of JARVIS, Tony Stark's digital butler. Bettany didn't wear any suits or make-up, he didn't train for fights nor wore costumes. He went to work, headed straight to the recording booth and then read his lines.

And since Bettany was having a blast on set, his other co-stars like Robert Downey Jr. (Tony Stark/ Iron Man) and Mark Ruffalo (Bruce Banner/ The Hulk) felt a bit jealous as they had to put in all the work. But all that changed as Bettany had taken on a bigger role in "The Avengers: Age of Ultron" as Vision.

No one knows how the Vision looks like but according to Cinema Blend, Bettany spent hours and hours on makeup just to get that perfect look for his character. It was a torturous make-up process and Downey and Ruffalo reportedly couldn't help but make fun of Bettany.

"There is no one I would rather have the delight of seeing in extreme discomfort than Paul Bettany," Downey laughingly said. Downey was even smiling while sharing that Bettany had to be frequently interrupted while filming scenes to touch up his makeup.

Ruffalo was one to poke fun at Bettany, too, especially after he realized that wearing Hulk's pajamas was way better than what Bettany was going through.

He said, "All I know is that I'm happy that I walk in and I leave the trailer, and I can go back an hour later and Paul Bettany's still in make-up. I'm 46 years old. That makes me feel good. Sorry, Paul."

"You should see him. He's like a specimen when he walks onto that thing. And he's like the perfect man. He's the Vision," Ruffalo proudly said.

So, how did Bettany take the long hours and constant makeup touch ups? He politedly said it is "the Brit approach to being boiled alive."

Watch out for The Vision in "The Avengers: Age of Ultron" on May 1, 2015.