He’s notched more first ascents than any other American mountaineer, wrote the definitive guidebook to a major North American mountain range, and at age 93, Fred Beckey is still plotting routes — though more slowly and buoyed by a cadre of fiercely protective partners.

For years, stories have floated around about the man known as much for his eccentric personality as for his singular obsession with climbing, said Alex Bertulis, 77, a retired Seattle architect who climbed with Beckey for decades.

Some were true, some not. “But that’s OK. That’s how legends are built,” Bertulis said.

Now, a documentary feature film in the works, “Dirtbag: The Legend of Fred Beckey,” is putting the spotlight on a man who has shied from such attention during decades of exploits. It is expected out next year.

Beckey is such a cult figure in North American mountaineering that tickets were snatched up within hours for a slideshow he recently presented in Seattle to help promote the film.

His body slightly stooped, blue dress shirt hanging loose off his frame, the nonagenarian needed help settling into his chair. Once lights were dimmed, he clicked through numerous slides, recalling from memory details about rock cracks, overhangs and other features on mountains in the Sierra and Cascades.

Beckey was born in Germany and immigrated to the United States as a child. His family settled in Seattle, where he got his first taste of hiking and scrambling with the Boy Scouts and later The Mountaineers club.

In 1942, he and his younger brother Helmut wowed the climbing community with an impressive second ascent of Mount Waddington in British Columbia.

He went on to accomplish hundreds of first ascents on peaks throughout the Pacific Northwest, Alaska, Canada and Wyoming. In 1954, he established new routes on three of Alaska’s mountains: McKinley, Deborah and Hunter. He also climbed in the Himalayas and China.

Beckey once wrote that climbing gave him a unique sense of control over his destiny. “The exaltation one can get in the presence of mountains can be a memorable lesson in humility and an aid to self-realization,” he wrote.

There will never be another Beckey because there are no more unclimbed mountains left to that degree, Bertulis said.

“Fred got the golden age of climbing first ascents,” Bertulis said. “That will be his legacy.”