Graham Chapman 8 January (1941)–4 October (1989) was my favourite Monty Python character, also the first to pass away at the untimely age of 48.
He was the lead character in the two movies of the group where there was a lead character.
His death has been witnessed and described by Michael Palin:
The regularity of his breathing is broken. A long pause, then a long inhalation. His lower jaw rises, his mouth closes and bares his lower teeth. I reach for my cup of tea. He breathes heavily. I start to talk again. A single tear emerges from his right eye and rolls down his cheek. The mouth is set. The great ridge of Adam's apple is still. There's no more noise from him. Nothing dramatic, no rattles or chokes or cries. He's not moving any more.