In this Aug. 31, 2007 file photo, artist LeRoy Neiman poses in his studio in New York. (Bebeto Matthews/ASSOCIATED PRESS)

LeRoy Neiman, a globetrotting artist whose celebrity often eclipsed that of the famous athletes and entertainers he portrayed in vibrantly colored, boldly expressive paintings, died June 20 at a hospital in New York. He was 91.

His publicist, Gail Parenteau, confirmed the death but said she did not know the cause. In 2010, Mr. Neiman had part of a leg amputated because of a circulation disorder.

By all accounts, Mr. Neiman was the foremost artist of the sporting world. He was the official artist of the Olympic Games five times and a regular presence at the Kentucky Derby, Super Bowl and international auto races for decades.

He was the artist-in-residence of the New York Jets football team and, in 1980, the official artist of the Democratic National Convention. He became so renowned for his paintings of boxers that he was inducted into the International Boxing Hall of Fame.

Mr. Neiman’s signature style included sheets of splashy color, yet the central figures of his paintings always remained recognizable and full of vigor. Though seldom loved by critics, his bright, colorful artworks managed to capture the glamour, spectacle and drama of sports.

Neiman, who is best known for his colorful and energetic paintings of sporting events, died Wednesday. (Courtesy of LeRoy Neiman Collection/COURTESY OF LEROY NEIMAN COLLECTION)

“LeRoy can do more with a paintbrush than a monkey can do with a peanut,” boxing promoter Don King once said. “LeRoy captures the universe, puts the image on canvas and gives it eternal life.”

Mr. Neiman contributed illustrations to Playboy magazine for more than 50 years, published dozens of books and sold paintings, drawings, prints and posters by the thousands. He became a millionaire many times over and adopted the persona of a dandy, with flamboyant white suits, an ever-present cigar, a luxuriant head of hair and a mustache that stretched almost ear to ear.

“When I sketched [dancer] Martha Graham,” he said to the New York Observer in 2001, “she told me vanity is very important. It makes you proud of what you do. I totally agree.”

He was for many years a fixture on television, called on to make instant illustrations during sporting events and elections. He portrayed presidents (Jimmy Carter), public figures (Robert F. Kennedy, Martin Luther King Jr.) and such cultural icons as Leonard Bernstein, Frank Sinatra, Mae West, Diana Ross, the Beatles and James Brown. Among athletes, a few of his countless subjects included Muhammad Ali, Joe Namath, Sandy Koufax and Jack Nicklaus.

“Often, Neiman’s mere presence at an event overshadows it,” a Sports Illustrated article noted in 1975. Once, while he stood on the sideline while the Jets were playing poorly, the crowd began chant, “Put LeRoy in!”

He appeared in three of Sylvester Stallone’s “Rocky” movies, twice as the ring announcer.

Mr. Neiman made his first sports paintings at the 1960 Winter Olympic Games in Squaw Valley, Calif. He covered the Indianapolis 500 in 1962 and, two years later, began a series of paintings of Ali. From then on, Mr. Neiman became the court painter of sports royalty.

Some of his paintings have sold for as much as $500,000, and his work can be found in the National Portrait Gallery and Baltimore Museum of Art. Yet Mr. Neiman has seldom been treated warmly by critics. Time magazine art critic Robert Hughes once dismissed his work as “slather.”

“Maybe the critics are right, but what am I supposed to do about it — stop painting, change my work completely?” Mr. Neiman told American Artist magazine in 1995. “I go back into the studio, and there I am at the easel again. I enjoy what I’m doing and feel good working.”

LeRoy Joseph Runquist was born in St. Paul, Minn., on June 8, 1921. When his mother remarried, he took the surname of a stepfather.

He served in the Army during World War II, including the Normandy invasion and the Battle of the Bulge, and painted murals on the walls of mess halls. After the war, he studied art at the Art Institute of Chicago, where he later taught figure drawing for 10 years.

While working as an illustrator for a department store, he met his wife, Janet Byrne, to whom he was married for 55 years. She is his only immediate survivor.

In Chicago in the 1950s, Mr. Neiman became friends with Hugh Hefner, who was just then publishing the first issues of Playboy. Mr. Neiman began contributing art to the magazine, including the popular “Femlin” character — a nude woman wearing thigh-high stockings, often sitting inside a champagne glass, to illustrate a page of jokes.

Hefner sent Mr. Neiman around the world to cover international high life for Playboy, including yachting, car races at Le Mans and the running of the bulls in Spain.

“Playboy made the good life a reality for me,” Mr. Neiman said in 1962, “and made it the subject matter of my paintings — not affluence and luxury, as such, but joie de vivre itself.”

Mr. Neiman contributed millions of dollars to charity, including $11 million to Columbia University for a center for the study of printmaking. His autobiography, “All Told: My Art and Life Among Athletes, Playboys, Bunnies, and Provocateurs,” was published two weeks before his death. His archives will be housed at the Smithsonian Institution.

Of all the sports he was asked to cover, Mr. Neiman said there was only one he refused to paint: professional wrestling. Once, in Canada, he was sketching the wrestler Mad Dog Vachon at ringside, when Mad Dog tore up his drawings.

“Next thing I know, I’m yelling at him and, all of a sudden, he throws me into the ring, then picks me up and starts spinning me over his head,” Mr. Neiman recalled in 1995.

“I’m seeing the arena lights go round and round and round and the crowd is going crazy and then ‘ooof!’ he tosses me out of the ring onto the floor. I messed up my arm.

“That was it. I wanted nothing to do with wrestling any more.”