Val Kilmer's Batman dream was "crushed" by the reality of wearing the Batsuit.
The 61-year-old actor portrayed the Caped Crusader in the 1995 film Batman Forever but hated the way the "ultimate leading role" was affected by the restrictive costume.
In the new Amazon Prime documentary Val — which tells the story of the actor's life, career and battle with throat cancer — his son Jack narrates the star's experiences on Joel Schumacher's film.
Recalling the moment he was offered the part, the Willow star said: "I was in shock and disbelief, mostly because I had just been exploring a remote bat cave.
"By Hollywood standards, Batman is the ultimate leading role and a dream come true. I took the part without even reading the script."
Val continued: "But whatever boyish excitement I had going in was crushed by the reality of the Batsuit."
He added, “Yes, every boy wants to be Batman. They actually want to be him…not necessarily play him in a movie.”
The costume was a pain to put on. "When you're in it, you can barely move and people have to help you stand up and sit down," he said.
"You also can't hear anything and after a while people stop talking to you, it's very isolating. It was a struggle for me to get a performance past the suit, and it was frustrating until I realised that my role in the film was just to show up and stand where I was told to."
Val also lamented that his co-stars Tommy Lee Jones and Jim Carrey were able to act unrestricted by their costumes, while he tried to be like "an actor on a soap opera" in scenes with Nicole Kidman, who played love interest Dr Chase Meridan.
The True Romance actor said: "Actors like Tommy Lee Jones had designed this whole performance, and so had Jim Carrey... It was just so huge I think it made no difference to what I was doing.
"I tried to be like an actor on a soap opera. The way I would turn to Nicole. Go count how many times I put my hands on my hips. I don't know how they come up with this style of acting but they seem to go, 'Go to soap opera school.'"