If you can’t picture actor Haruo Nakajima’s face, that’s because his most famous movie role had him hidden inside a monster costume. The Japanese performer—who played cinema’s most famous reptilian beast, Godzilla, in both the 1954 original film and 11 sequels—died on August 7, 2017 at the age of 88 from pneumonia, but not before giving the world a glimpse of the man beneath the scaly suit.

Nakajima was born on January 1, 1929, in Yamagata, Japan. As the third of five children, he knew he wouldn't inherit his father's butcher shop (which traditionally went to the eldest son), so he enrolled in an acting program at the age of 18 after working for a brief period as a truck driver for the occupying Allied forces.

Nakajima launched his movie career by working as a stuntman in samurai movies. His most famous bit part was in Akira Kurosawa’s famous 1954 adventure-drama Seven Samurai, but his big break occurred while filming the 1953 World War II military film Eagle of the Pacific.

The script required Nakajima to jump from a burning plane, and when director Ishirō Honda saw him in action, "he thought, 'This guy is full of energy,'" the actor recalled to Great Big Story in March 2017. “They came to see me as someone who had guts, and I think that’s why they wanted me for the role of Godzilla.”

In the original 1954 Godzilla film, underwater hydrogen bomb testing disturbs an ancient sea creature from its aquatic habitat, and the beast proceeds to wreak havoc upon mainland Japan. Since Nakajima initially had no idea what the titular monster would look like or how it would move, he prepared for his role in an unusual way.

“I spent 10 days at the zoo,” Nakajima later recalled, according to Jonathan Clements’s book Schoolgirl Milky Crisis: Adventures in the Anime and Manga Trade. “I’d watch the way the elephants walked, the monkeys, the gorillas, but especially the bears. I used to take two lunches with me. One was mine, and the rest of it I’d throw to the bears. When one of them snatched it up and shoveled it into his mouth, I’d watch the way he did it.”

Not that it was easy to move in the Godzilla suit. The original costume was made from ready-mixed concrete (rubber was a scare commodity in post-war Japan) and reportedly weighed around 220 pounds. It was also suffocatingly hot: Nakajima sweated so much beneath the soundstage’s bright lights that by day’s end he said he could fill half a bucket with perspiration wrung from his undershirt.

When Godzilla first arrived in movie theaters in 1954, an anonymous Nakajima watched the film from the front row to gauge the audience's reaction. "When the film was a success I was so surprised," he told Great Big Story. "I was so happy."

Nakajima starred in Godzilla movies for most of the next two decades. He also appeared in dozens of other monster movies as a contract actor for Japanese film studio Toho, which created the Godzilla franchise. But after filming Godzilla vs. Hedorah in 1971, Nakajima's exclusive contract wasn't renewed, and he donned the scaly suit just one last time for 1972's Godzilla vs. Gigan. The actor retired in 1973, and spent his remaining years attending comic cons and movie conventions, making the occasional Godzilla film cameo, and running a Toho-owned mahjong parlor.

Even though Nakajima enjoyed a successful career, he would never experience international fame: "Back then, people didn't speak positively of suit actors," Nakajima told Japanese magazine Josei Seven in 2014, according to Kotaku. "There'd be whispers going around that working inside [a suit] is not an acting job."

Yet the Godzilla franchise became a worldwide phenomenon. The films ushered in a new era of sci-fi monster movies, and after World War II, they served as a campy—yet palpable—reminder of the dangers of nuclear combat.

As for Nakajima himself, “there are not a lot of actors that you can compare him to,” Akira Mizuta Lippit, a cinematic arts professor at the University of Southern California, told The Washington Post after Nakajima’s death. “He, in fact, invented the kind of acting that he then performed. In that sense, he’s absolutely unique."