From Van Damme’s Wikipedia page-

Van Damme worked for director John McTiernan for the film Predator (1987) as an early (eventually abandoned) version of the titular alien, before being removed and replaced by Kevin Peter Hall.[42] As the first choice to play the titular Predator character, with the intent that he would use his martial arts skills to make the alien an agile, ninja-like hunter, but after few days shot, he left the film. It was reported that Van Damme constantly complained about the monster suit being too hot and causing him to pass out; he allegedly also voiced reservations about only appearing on camera in the suit. Additionally, it became apparent that a more physically imposing actor was needed to make the creature appear threatening against the team of soldiers. The role eventually went to Kevin Peter Hall.[43] After Predator was a success, Van Damme said that he appreciated the movie and that he had no regrets about missing that role.