Washington ? A star-studded lineup of comedians including Chris Rock, Dave Chappelle, George Lopez, Kathy Griffin and Arsenio Hall honoured Eddie Murphy on Sunday as an "American icon." The Kennedy Center for the Performing Arts presented the comedian with the Mark Twain Prize, the nation's top prize for humour. The evening's most emotional tribute came from Saturday Night Live alum Tracy Morgan, who received a standing ovation from the audience. He called Murphy his "comedic hero." Morgan survived a serious car crash last year that left him in a coma.