HE fights L.A.’s scariest criminals every week on “The Shield,” but Michael Chiklis found a much more intimidating foe on the “Fantastic Four” set: his own costume.

“His initial reaction was a little bit of a surprise,” says creature effects supervisor Mike Elizalde. “In makeup for the first time, he felt very constricted and unable to move. He said, ‘You know what, guys, this feels horrible. I don’t know if I can do this.’ “

Elizalde wasn’t the only one who was surprised by Chiklis’ aversion to being encased in a heavy latex suit of fake orange rock.

The actor himself had to reassess whether he could take on the role he’d been dreaming of since childhood.

“I became terrified I wouldn’t be able to do the movie,” says Chiklis, who eventually sought help from a psychiatrist to talk though his fears about being unable to escape from the costume.

Chiklis overcame his initial phobia of being in the suit – but he still struggled with occasional reservations. “I hated knowing I couldn’t get out unless six people helped me,” he says. “It was really a trust exercise for me.”

Psychological issues aside, the endurance aspect of wearing the 60-pound suit, plus prosthetic makeup and dentures, became a daily physical test for Chiklis.

He described the experience as akin to “wearing a Bowflex.”

Unable to sit down, the actor would rest by leaning against a slant board that had been specially prepared for him, while effects people hooked him up to a cooling system.

Chiklis’ performance in the suit, says the effects supervisor, is a testament to both the actor’s talent and his tenacity.

“When you take a principal actor who hasn’t had any experience with this stuff, and you see the performance he turns in, it says a lot for what he overcame.

“I think the Thing will be memorable.”