January 8, 1941 - October 4, 1989: Age 48
Graham Chapman is most famous for being one-sixth of Monty Python's Flying Circus. His characters include Hegel in the International Philosophy football match; Mrs. Conclusion, who discusses philosophy with Jean-Paul Sartre; Arthur, King of the Britons in Holy Grail; and Brian in Life of Brian. He went to Cambridge University and qualified as a medical doctor, but never practiced. Instead he began writing comedy with fellow student John Cleese.
Chapman was also one of the first gay celebrities to come out publicly: he did so on a television talk show in the mid-1970s.
In 1988 Chapman's dentist noticed a growth on his tonsils. It was diagnosed as throat cancer. It had spread to his neck and spine, and within a year of diagnosis he died of pneumonia. It was one day before the 20th anniversary of the first broadcast of Flying Circus: "The worst case of party-pooping in history," according to Terry Jones. His old friends John Cleese and Michael Palin were with him when he died.
At the memorial service in December, John Cleese delivered a eulogy. I won't spoil it by telling you much, just that the first few words are "Graham Chapman, co-author of the parrot sketch, is no more." It's on YouTube: just go there now and enjoy it. Here is the link.
Sources: Wikipedia, YouTube