Simpsons producer Sam Simon died Monday after battling colon cancer. The writer and producer was instrumental in the early days of The Simpsons, helping design a number of its most iconic characters.

Revisit some of his key creations below, and see photos of them here.

Mr. Burns

The Springfield magnate and boss of Homer Simpson first appeared in the season one episode "Simpsons Roasting on an Open Fire."

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Chief Wiggum

The incompetent Springfield police chief made his debut in 1990's "Homer's Odyssey," with Hank Azaria voicing the character since his debut.

Eddie

Eddie, one of Wiggum's right-hand men, isn't the sharpest tool in the shed, but he isn't quite as dimwitted as the chief. Voiced by Harry Shearer, Eddie first appeared in the 1990 season one episode "There's No Disgrace Like Home."

Lou

The smartest member of the Springfield Police Department, Lou also first appeared in "There's No Disgrace Like Home." He is voiced by Hank Azaria.

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Dr. Hibbert

The venerable physician, who first appeared in the season two episode "Bart the Daredevil," is so good natured that someone was able to assemble a 10-hour supercut of him laughing from the show. Harry Shearer has voiced the character since his 1990 debut.

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Bleeding Gums Murphy

Lisa's saxophone idol appeared in four episodes, voiced by Ron Taylor, Daryl Coley and Harry Shearer. First appearing in 1990's "Moaning Lisa," his death in 1995's "Round Springfield" was the linchpin to one of the most poignant episodes of the series.

'The Raven'

Simon came up with the idea to adapt Edgar Allan Poe for the 1990 Halloween special. Simpsons creator Matt Groening said in the season two commentary that he worried the segment would be the "most worst, pretentious thing" the show had ever done. But it was ultimately hailed as a success and is still remembered today. Teachers even use it to teach the classic poem.