Christopher Johnson McCandless was born in El Segundo, California. He was the first child of Wilhelmina "Billie" McCandless (née Johnson) and Walter "Walt" McCandless. The couple subsequently had one more child, a daughter named Carine. McCandless also had six half-siblings from Walt McCandless' first marriage, who lived with their mother in California. Author Jon Krakauer later speculated that Walt's transition between these two marriages may have deeply affected and profoundly shaped McCandless' world-view.

In 1976, the family relocated to Washington, D.C., and settled in suburban Annandale, Virginia, when McCandless' father was hired as an antenna specialist for the National Aeronautics and Space Administration (NASA); McCandless' mother worked as a secretary at Hughes Aircraft. The couple went on to establish a successful consultancy business out of their home, specializing in Walt's area of expertise.

McCandless graduated from W.T. Woodson High School in Fairfax, Virginia, in 1986. He excelled academically, although a number of teachers and fellow students observed that he "marched to the beat of a different drummer." McCandless also served as captain of the cross-country team, where he would urge teammates to treat running as a spiritual exercise in which they were "running against the forces of darkness ... all the evil in the world, all the hatred."

In the summer of 1986, McCandless traveled to Southern California and reconnected with distant relatives and friends. It was during this journey he learned that his father had not yet divorced his first wife when McCandless and his sister Carine were born and had apparently maintained somewhat of a double life before the move to Virginia. It is speculated that this discovery had a profound impact on the younger McCandless.

By the end of summer in 1990, McCandless had driven his Datsun through Arizona, California, and South Dakota, where he worked at a grain elevator in Carthage. A flash flood disabled his car, at which point he removed its license plates, took what he could carry, and kept moving on foot. His car was later found, repaired, and put into service as an undercover vehicle for the local police department.

McCandless graduated from Emory University in May 1990, with a bachelor's degree in the double majors of history and anthropology. After graduating, McCandless donated his college savings of $24,000 to OXFAM and adopted a vagabond lifestyle, working when necessary as a restaurant food preparer and farmhand. An avid outdoorsman, McCandless completed several lengthy wilderness hiking trips and paddled a canoe down a portion of the Colorado River before hitchhiking to Alaska, in April 1992.

McCandless' final written journal entry, noted as "Day 107", simply read, "Beautiful Blue Berries." The days 108 through 112 contained no words and were marked with only slashes, while on Day 113 there was no entry.

In April 1992, McCandless hitchhiked from Carthage, South Dakota, to Fairbanks, Alaska. As noted by Krakauer, McCandless was last seen alive at the head of the Stampede Trail on April 28, 1992, by a local electrician named Jim Gallien. Gallien had given McCandless a ride from Fairbanks to the start of the rugged track just outside the small town of Healy. Gallien later said he had been seriously concerned about the safety of McCandless (who introduced himself as "Alex"), after noticing McCandless' light pack, minimal equipment, meager rations, and obvious lack of experience. Gallien said he had deep doubts about "Alex's” ability to survive the harsh and unforgiving Alaskan bush.

After hiking along the snow-covered Stampede Trail, McCandless came upon an abandoned bus (about 28 miles (45 km) west of Healy at 63°52′5.96″N 149°46′8.39″W) alongside an overgrown section of the trail near Denali National Park. McCandless, according to Into the Wild, attempted to continue "heading west until I hit the Bering Sea." However, he was deterred by the thick Alaskan bush and returned to the bus, where he set up camp and attempted to live off the land. He had 4.5 kilograms (9.9 lb) of rice, a Remington semi-automatic rifle with 400 rounds of .22LR hollowpoint ammunition, a number of books, including one on local plant life, some personal effects, and a few items of camping equipment. Self-portrait photographs and journal entries indicate he foraged for edible plants and hunted game. McCandless hunted porcupines, squirrels, and birds, such as ptarmigans and Canada geese. On June 9, 1992, he stalked and shot a moose. However, the meat spoiled within days after McCandless failed to properly preserve it.

On September 6, 1992, multiple hunters who were looking for shelter for the night came upon the converted bus McCandless had been staying in. Upon entering, they smelled what they thought was rotting food and discovered "a lump" in a sleeping bag. The hunters quickly radioed police, who arrived the following day. They found McCandless's decomposing remains in the sleeping bag. It is theorized that he died from starvation two weeks before the body was found.

Into the Wild is a 2007 American biographical adventure drama film written, co-produced, and directed by Sean Penn. It is an adaptation of the book of the same name written by Jon Krakauer and tells the story of Christopher McCandless, a man who hiked across North America into the Alaskan wilderness in the early 1990s. The film stars Emile Hirsch as McCandless and Marcia Gay Harden and William Hurt as his parents and features Jena Malone, Catherine Keener, Brian Dierker, Vince Vaughn, Kristen Stewart, and Hal Holbrook.