Filming classic Japanese monster movies like Godzilla was often a grueling experience for the actors in the monster suits.
The suits weighed 100 to 200 pounds. Most took about three hours to put on. The suits were especially dangerous when the monsters emerged from underwater.
Actor Kenpachiro Satsuma played Godzilla and other monsters in the 1980s and 90s. He often passed out in the poorly ventilated suits.
In Godzilla vs. The Smog Monster, Satsuma played Hedorah, the smog monster. While filming he was struck with appendicitis. Doctors had to remove Satsuma’s appendix while he was still in the monster suit. It would have taken too long to get him out of the costume.
The Forrest Ackerman papers at UW's American Heritage Center contain publicity photos from several Godzilla movies.