Aron Lee Ralston is an American mountaineer, mechanical engineer, and motivational speaker, known for surviving a canyoneering accident by cutting off part of his own right arm. On April 26, 2003, during a solo descent of Bluejohn Canyon in southeastern Utah, he dislodged a boulder, pinning his right wrist to the side of the canyon wall. After five days, he had to break his forearm, amputate it with a dull pocket knife to break free, make his way through the rest of the canyon, rappel down a 65-foot (20 m) drop, and hike 7 miles (11 km) to safety.

The incident is documented in Ralston's autobiography Between a Rock and a Hard Place and is the subject of the 2010 film 127 Hours in which he is portrayed by James Franco. After the accident, he continued mountaineering and became the first person to ascend all of Colorado's fourteeners solo in winter.

Aron Ralston grew up in the Midwest before moving to Colorado at the age of twelve, where he became an avid outdoorsman. In 2002, he gave up a career as a mechanical engineer in New Mexico and moved to Aspen, Colorado, where he continued his attempt to climb the fifty-nine Colorado peaks of more than 14,000 feet solo in winter.

Since his accident, he has resumed his life of adventure and discovery.