Robert Rauschenberg, who died Monday at 82, was a foundational figure in American art. He helped spark the Pop Art movement and stayed in the forefront of the art scene, from the 1950s until his Metropolitan Museum of Art retrospective in 2005, as an enfant terrible-cum-éminence grise.

His busy, collage-like constructions were originally constructed of detritus that in some cases were the only materials the impoverished young artist could afford. Conceived as a reaction against the sterile Abstract Expressionism that dominated in his early years, they became a byword for creativity and inspired generations of younger artists.

A genre breaker and category crosser whose playful, capacious spirit reminded many of Walt Whitman, Rauschenberg famously said: “Painting relates to both art and life. Neither can be made — I try to act in the gap between the two.”

This attitude often gave his work an open-ended, unfinished feel, something the artist didn’t deny. “I like things that are almost souvenirs of creation, as opposed to being an artwork,” he told Harper’s Bazaar in 1997. “The process is more interesting than completing stuff.”

On canvasses festooned with stuffed birds, Coke cans, and cloth tatters, Rauschenberg created collages that could be seen as a three-dimensional equivalent of John Cage’s randomly assembled music. The two were friends and collaborators from their art school days, when they studied together at Black Mountain College in North Carolina under Josef Albers, although Albers, an epitome of Bauhaus formalism, loathed Rauschenberg’s chaotic spirit.

Rauschenberg’s most famous early pieces include “Bed” (1955), the artist’s pillow and quilt painted blood-red, and “Monogram” (1959), a stuffed angora goat with a rubber tire around its waist. Of the sustained power of “Monogram” to inspire, a critic for Art in America wrote in 2006: “It looks shockingly original and only barely like art.”

Earlier critics were sometimes less kind. L’Osservatore Romano deplored his 1964 win of the Venice Biennale Grand Prize as “the total and general defeat of culture.” When a critic in Florence suggested that Rauschenberg toss his latest work — assemblages of sticks and stones — into the river, the artist complied. This was no Abstract Expressionist creator. Quite the opposite: He once spent a week erasing a Willem de Kooning drawing, then exhibited the blank page. Citing his openness to new experience, the critic Robert Hughes dubbed Rauschenberg “The Great Permitter.”

Born October 22, 1925 in Port Arthur, Texas, Milton Ernest Rauschenberg (as he was Christened) was the son of a utility company executive who bred bird dogs. His mother was a talented seamstress who sewed him shirts out of tatters. Rauschenberg initially contemplated joining the ministry, but he said he opted against it because his parents’ fundamentalist church forbade dancing. He discovered a talent for drawing while in the Navy during World War II. He enrolled at the Kansas City Art Institute under the GI Bill. Later studies took him to Black Mountain, where he met what would become a formative generation of American artists, including John Cage, the painters Franz Kline and Cy Twombly, as well as the choreographer Merce Cunningham, another frequent Rauschenberg collaborator over the years. Around this time he renamed himself “Robert.”

He moved to New York in the early 1950s and embarked on a series of all-black and all-white paintings. Later, he began making art from junk he rescued from the streets. He called the resulting pieces “combines.” Though earlier married and divorced, he formed a creative and intimate union with Jasper Johns. “Jasper and I literally traded ideas,” he once told the critic Calvin Tomkins. “He would say, ‘I’ve got a terrific idea for you,’ and then I’d have to find one for him.” They supported themselves decorating windows for Bonwit Teller and Tiffany & Co.

In the 1960s, Rauschenberg’s combines began including contemporary events, notably images of President Kennedy and the space program. In the mid-1960s, he collaborated with the laser scientist Billy Kluver to form the nonprofit EAT foundation (Experiments in Art and Technology) that pioneered the use of scientifically-generated imagery in multimedia happenings. He danced and created sets for Merce Cunningham’s dance troop, and later collaborated with Trisha Brown.

In the 1970s and 1980s, he traveled extensively and created the Rauschenberg Overseas Cultural Interchange to facilitate international understanding. With the money his works now commanded, he could afford to bankroll it himself. He became the largest landowner on Florida’s Captiva Island and split his time between there and Greenwich Village. In recent years he founded Change Inc. to help struggling artists pay their medical bills.

An old-school drinker reputed to put away a bottle-and-a-half of Jack Daniels daily, he gave it up a few years ago when his health deteriorated. Although he dried out briefly at the Betty Ford Center, he soon went back to drinking wine.

“One of the things they teach you at Betty Ford’s is, ‘Don’t ever be without something to drink,'” he told the New Yorker’s Calvin Tomkins in 2005.

Mr. Tomkins asked if that didn’t mean something nonalcoholic.

“That’s what she means!” the artist cackled.