Fred Beckey, a fabled mountaineer and author who was the first to take hundreds of routes to the summits of North America’s tallest peaks in Alaska, the Canadian Rockies and the Pacific Northwest in an audacious seven-decade climbing career, died on Monday in Seattle. He was 94.

Megan Bond, a close friend of Mr. Beckey’s, wrote in a Facebook message that he died of congestive heart failure in her home. A longtime resident of Seattle, he had been in hospice care for four days, she said.

Rawboned and tenacious, Mr. Beckey made as many as a thousand ascents that no one was known to have taken before. He wrote a dozen books on mountaineering, many of them considered definitive guides to the terrain of the continent’s best-known and least accessible peaks.