The 86-year-old TV personality and former late-night sidekick died this morning surrounded by his family at Ronald Reagan UCLA Medical Center in California, his agent Howard Bragman said.
McMahon had a "multiple of health problems the last few months," Bragman said, though he declined to name the entertainer's cause of death.
A person close to the TV personality told the Associated Press that he had bone cancer, among other ailments, and had been hospitalized for several weeks.
Earlier this year, McMahon had been hospitalized in intensive care with pneumonia and other illnesses.
McMahon liked to keep his role on the "Tonight Show" in perspective.
"He trusted me," McMahon said of Carson. "A good sidekick gets in and gets out without causing any damage."
He said the highlight was after Carson's monologue when the duo would banter before the guests arrived.
In an AP interview, McMahon described the exchange as "a free-for-all." Carson, who McMahon called a brother, died in 2005.
McMahon got his start right here in Philadelphia at WCAU in 1949. He worked in the Philadelphia market for nine years as a clown on “Big Top”, the nephew on the cooking show “Aunt Molly’s Den”, hosted “Cold Cash” and “Million Dollar Movies”, and other projects.
His last show was “Five Minutes More”, commentary at the end of the 11 p.m. newscast, according to the Philadelphia Inquirer.
“I was the producer and was only 21,” Jim Hirschfield told the paper. “Ed and I met everyday for lunch at Cynwyd Lounge on City Avenua and wrote the show over two martinis and a hamburger.”
During his time working in Philadelphia, McMahon lived in Drexelbrook apartments in Drexel Hill in the 1950s—right next door to Dick Clark, the paper reported.
“Fifty years ago, Ed and I were next-door neighbors in Philadelphia,” Clark told the Inquirer. “Over the years, our friendship grew while he became one of America’s favorite television personalities. We were together for years. Ed was a big man, had big talent and a really big heart. We’ll all miss him.”
The famous TV pitchman -- who is responsible for bringing the infamous "Heeeere's Johnny!" line into the pop culture lexicon -- has promoted a number of products through the years such as Budweiser, American Family Publishers' sweepstakes and, most recently, Cash4Gold.com in a self-deprecating Super Bowl commercial.
McMahon also hosted the popular syndicated talent competition "Star Search."
But the Hollywood legend fell on hard times recently and became embroiled in financial trouble.
His home was reportedly to be placed on the auction block later this month after he fell behind $644,000 on his $4.8 million mortgage.
"Last year, when the news came out that he was potentially losing his house, he said, 'I want to stand up and tell the world that I made a mistake. I want people to know that I can go through this and they can go through this with dignity with their heads held high,'" Bragman said. "He was inspirational to others."
He recently settled lawsuits against a hospital and doctors over difficulties stemming from the broken neck he suffered in fall of 2007. In 2002, he sued various insurance companies and contractors over mold in his house and collected a $7 million settlement.
Born in Los Angeles, McMahon grew up in Lowell, Massachusetts. During World War II, he was a Marine aviator, flight instructor and test pilot. Discharged in 1946, McMahon graduated from The Catholic University of America in 1949.
In the 1950s, he emceed the game shows "Missing Links," "Snap Judgment," "Concentration" and "Who Dunnit?" before returning to active duty in the Korean War in 1953.
He remained in the Marine Corps Reserve, retiring with the rank of Colonel in 1966 and was then commissioned as a Brigadier General in the California Air National Guard.