Domo-kun was created in 1999 for a series of eighteen stop motion animated shorts commemorating the 10th anniversary of NHK's BS (broadcast satellite) service. As of this writing, all of the episodes are available on YouTube through a search for "domo-kun."
He is a big brown furry box with arms, legs and a gaping red mouth. In episode 1, he hatched from an egg which fell into the underground home of Usajii, an elderly-looking rabbit who likes to drink hot tea and watch TV all day. Domo-kun's first sight after popping out of the egg was to watch the famous NHK announcer Shizuo Yamakawa say "domo," and so he continued to mimic the word throughout the series—hence the name "Domo-kun."
The first few episodes consisted of Domo-kun and Usajii watching various types of programs, to which Domo-kun would often react in some hilarious way (jumping around to rock music, for instance) while Usajii would try to calm him down. Two bats hanging from the roof, Shinobu and Morio, provided color commentary. A fifth character was added later: Taachan, a female weasel who became friends with Domo-kun and Usajii.
Although the shorts stopped airing in 2000, Domo-kun remained very popular. He stayed on as a BS mascot until 2004, when he was replaced by a lame dog-like character named Nanami-chan. NHK would often bring a person in a Domo-kun costume to public events, and the big Domo-kun also made cameo appearances in the annual Red and White Song Battle. (Big Domo-kun speaks with a voice provided by Tessho Genda, a well-known voice actor who is often called in to dub Arnold Schwarzenegger movies.) Stuffed Domo-kuns also became popular among Japanese kids.
Then came Fark, whose readers picked up on Domo-kun early on and began using him in their popular Photoshop contests. In 2002, Farkers created an image of two Domo-kuns chasing a kitten, with the caption "Every time you masturbate, God kills a kitten." The (bizarre) popularity of this image helped spread Domo-kun awareness among bored young people across the English-speaking world. b3ta, Something Awful and other sites jumped on the bandwagon as well.
The story is not over, though. In 2006, Nickelodeon announced that it was co-producing a new Domo-kun series, which will be shown on Nick before being shown on NHK in Japan. The new series will consist of 26 shorts, each 2 minutes long, and will mark the first time Nick has used a Japanese animation property since... those weird Saban shows they used to air in the late 80's. Domo-kun lovers will have much to look forward to in the near future.
- Japanese and English Wikipedia articles