NEW YORK (Reuters) - LeRoy Neiman, whose distinctive, vibrantly colored paintings of sports figures and athletic events made him as famous as many of the athletes he drew, died on Wednesday at age 91. Neiman, a showman known for his handlebar mustache, sometimes painted live on television during major events such as the Olympics and the Super Bowl, helping make him one of the world's most commercially successful contemporary artists. Among his subjects were boxing's Muhammad Ali, former New York Jets football star Joe Namath and baseball greats Mickey Mantle and Joe DiMaggio. Neiman had just published his memoirs, "All Told," which came out days before his 91st birthday on June 8. He had a happy birthday. He was so happy to see his memoir published," said Gail Parenteau, his publicist. She said he died at Presbyterian Hospital in Manhattan of natural causes. He had been hospitalized there in 2010 with vascular problems that required life-saving surgery to remove his right leg above the knee, she said. By coincidence, his latest work - a multicolored golf ball 4 feet in diameter and completed in April - went on display in Chicago on Wednesday, said his archivist, Tara Zabor. Neiman was born in St. Paul, Minnesota, on June 8, 1921, and was of Turkish and Swedish descent "as near as I can figure out," according to his official website. A child of the Great Depression whose father abandoned his family at a young age, Neiman enlisted in the U.S. military in 1942, later taking part in the invasion of Normandy and fighting in the Battle of the Bulge, according to a biography provided by Parenteau. On returning home, he attended Chicago's School of the Art Institute on the G.I. Bill. He became a contributing artist for Playboy magazine in the 1950s and established a friendship with its founder, Hugh Hefner, one of many famous friends including Frank Sinatra and Ali. He painted about a dozen portraits of Ali, Zabor said, befriending the boxer when he was still known as Cassius Clay. Neiman said he ignored advice that working with Playboy would ruin his career as a legitimate artist. "But Playboy was liberating," he wrote in his memoir. I was drawn to it and went for it full throttle. ... I lived my life as I wanted to live it and screw what happens. I always stayed in tune with my own ambitions and attitudes and I'm still my intractable old self, for better or worse. Patty Otis Abel, a contributor and editor on his memoir, said Hefner appreciated that Neiman came from a fine arts background. "Hugh wanted to be able to combine a fine art and more of a commercial sensibility, and he felt that's what LeRoy brought," Abel said. Neiman was named official artist of the Olympic Winter Games in Lake Placid and Sarajevo in 1980 and 1984 and the 1984 Summer Games in Los Angeles, cementing his image as a painter of athletic themes. He also painted U.S. presidents, jazz musicians, Las Vegas gamblers and the animals of Africa in addition to authoring 15 books. Abel agreed he was a showman. "There was always a genuine aspect to it," she said. It was never phony. This was a genuine guy and a true original. Reporting By Daniel Trotta; editing by Christopher Wilson