Ed McMahon, best known as Johnny Carson's sidekick on NBC's Tonight show ("And now h-e-e-e-e-e-ere's Johnny!"), died early today (Tuesday) in Los Angeles at age 86. The cause of death was not disclosed, but his publicist, Howard Bragman, said that McMahon had a "multitude of health problems the last few months." The Associated Press, quoting a source close to McMahon, said that he had been battling bone cancer and had been hospitalized for several weeks.