The character of Butters is based on Eric Stough, who is regularly credited 'Director of Animation'.
Butters first speaks in Season 3, the episode 'Two Guys Naked in a Hot Tub'
Butters birthday is September 11th. This is revealed in the episode 'AWESOM-O'.
Butters first made an appearance back in episode one Cartman Gets an Anal Probe (Pilot)
Butters has a very small role in the South Park Film 'Bigger Longer and Uncut', being the first one to touch Cartman after he see's Asses of Fire
Butters was properly introduced as a character in Season 3's episode 'Two Guys Naked in a Hot Tub'. Before that he was a background character, once being refered to as Swanson in Seasons 2's 'Conjoined Fetus Lady'.
Butters' Very Own Episode (Season 5) sets up the characters family and past, revealing his Father is Gay and his Mother tried to kill him!
He temporarily takes over as Kenny's replacement in Season 6, after Kenny dies at the end of Season 5. He is later replaced by Tweek.
It is revealed in Season 10 that Butters was sexually abused by his Uncle Bud.
Butters took on the alter ego 'Professor Chaos' in Season 6 after being rejected from the group for being 'too lame'. This leads to a desire for revenge on Butters behalf. Not only for the way the boys have treated him, but also society and his parents.
Professor Chaos is based on Marvel Comics villain Dr.Doom.
Paris Hilton offers $200 million dollars to buy Butters in 'Stupid Spoiled Whore Video Playset'. His parents ask for $250 million and the deal is made.
Butters dresses up as a girl in 'Marjorine' (Season 9) to go undercover at a slumber party. He also fakes his death in this episode.
One of the rare times Butters swears is in Christian Hard Rock (Season 7) saying to Cartman 'Fuck You, Eric!' whilst giving him the finger!
We see Butters first experience smoking in Miss Teacher Bangs a Boy (Season 10).
Music and dancing are two of Butters favourite past times. He is often singing his catchprase 'Loo loo loo' song.
Butters is quite often heard using his catchphrase 'Oh Hamburgers!' instead of a swear word.
Butters likes to describe unpleasent things like this:
'Oooh its all sticky'
'Oooh its all gooey'
'Oooh its all icky'
'Ooh its all squiggy'
(See the Quotes Section for more!)
Butters tends to be the 'tester' of the group. He is often picked on to try things before the others, like put on a Condom in Season 5's 'Proper Condom Use'.
Although Cartman likes to rip on Butters a lot, he is always the one he turns to when the others aren't willing to help. For example The Death of Eric Cartman (season 9), Marjorine (season 9), Go, God. Go! Part II (season 10).
Butters is a fan of star trek, solving the argument between the two trekkies in the season 4 episode, 4th Grade.
There is some question as to whether Butters is abused by his parents. At best their parenting techniques leave a lot to be desired. For example, threatening Butters with SUPER AIDS, grounding him for getting fat and the fact his mother tried to kil him in 'Butters Very Own Episode'.
Butters accidentally is given a Porn film to watch by his parents, instead of The Lord of The Rings: The Two Towers.
Butters is sent to Gay Concentration Camp when his father mistakenly thinks hes gay. I won't spoil it for you, but I would recommend you watch 'Cartman Sucks' in Season 11.
He shaves his blonde crop off when he joins David Blaines Cult in Season 5's 'Super Best Friends'.