Secret ‘Avengers’ cameo: Lou Ferrigno helped voice the Hulk

Shirtless. Green. Huge. Very very angry.

In "Marvel's The Avengers," Mark Ruffalo plays The Hulk, but it turns out he received help from someone who knows a lot about the character: Lou Ferrigno.

I'll explain.

[Related: 'Avengers' news: sequel is happening, makes $702 million]

Ferrigno played the post-transformed green monster in "The Incredible Hulk" television show from 1978-to-1982. (In all fairness, the late Bill Bixby played Dr. David Bruce Banner on the show -- which is the part Ruffalo plays in live-action in the film).

Ferrigno was called upon to help voice the new Hulk in "The Avengers." Oddly, he did not voice his own television character, but did lend his voice to previous Marvel "Hulk" movies in 2003 and 2008.

Oscar-winning sound editor Christopher Boyes, who crafted the voice of the "Avengers" Hulk, recently explained in a SoundWorks Collection interview (video also below):

"Initially for Hulk, I started using all sorts of animal vocals and tried to create this larger-than-life, territorial rage... And so the feedback coming back from Joss [Whedon] was that it was too much of a monster, too much of a creature. He really wanted to lead with the notion that this is a superhuman, but human in rage."

Boyes goes onto explain that he showed Whedon a bunch of examples that he experimented with, and the one he liked the most "turned out to be [a combination of] Mark Ruffalo, some Lou Ferrigno and a little bit of me and two people from New Zealand. So I led with that."

[Related: 'The Avengers' spoiler: Who was revealed in the final scene?]

Boyes added that Ferrigno "had a real knack for who this character was," which is one reason he was kept in.

The 6-foot-5-inch actor, now 60 years old, has worked steadily in film and television over the years. And for all the voice over work he's been doing, you might not know that he lost roughly 80 percent of his hearing as a child. He wears hearing aids and has said in past interviews that the issue helped him become more determined in life.

[Related: 'Growing Pains' child star's 'Avengers' role]

As for who voiced the growls for the television Hulk back in the day: It was Ted Cassidy, most famous as Lurch on "The Adams Family." Cassidy, who also recited the opening narration of "The Incredible Hulk," died in 1979. His human growls were replaced by dubbed animal growls for the remaining years of the show.

Watch more clips from 'Marvel's The Avengers':

Clip: Interrogation Clip: Face Off Clip: Desperate Clip: Another Bout