Bonsai Kittens was an Internet hoax website claiming that kittens could be made into decorative ornaments by sealing them in glass containers, which forced their bodies to mold into various shapes. The site became the subject of controversy online in 2001 after many animal rights groups filed complaints for its removal, while others defended the existence of the website as a work of satire protected by free speech.
On December 20th, 2000, a group of MIT graduate students launched the website BonsaiKitten under the alias "Dr. Michael Wong Chang." The site featured a how-to guide for making Bonsai Kitten sculptures and a gallery of fabricated Bonsai Kitten images. The website was initially hosted by MIT but it later relocated to a commercial provider. The site's domain BonsaiKitten.com has since become defunct and now it redirects to a ThinkGeek product page for a Bonsai Kitten plush toy, but a mirror of the original site is available on Ding.net.
Precursor: Square Watermelons
The hoax bears many similarities to the Japanese practice of growing square watermelons. On June 15th, 2001, BBC News published an article titled "Square Fruit Stun Japanese Shoppers", which reported that Zentsuji farmers had invented a practice 20 years prior of growing melons in glass boxes to make the fruits more conducive to storage.
In December of 2000, the Humane Society of the United States (HSUS) posted a bulletin denouncing the site. On December 22nd, MIT removed the site due to complaints from citizens and other animal rights organizations. After the site resurfaced under the commercial host WEB2010 in January of 2001, the HSUS contacted the provider and the site was taken down again on January 17th, but it immediately returned under an unknown host. On February 22nd, the Associated Press released an article titled "Animal Lovers Not Laughing About Joke Internet Site 'Bonsai Kitten'", revealing that over 25 mirror sites had been shutdown by web providers after receiving similar complaints. The online urban legend repository Snopes includes an entry on Bonsai Kittens labeled as a "false" claim, which features a statement by an anonymous Bonsai Kitten creator who revealed that the website was meant to be satirical. On July 16th, the "antibonsaikittenssociety" Yahoo Group was created. On February 9th, the technology news site Wired published an article titled "FBI Goes After Bonsaikitten.com", reporting that the FBI were investigating the website for violating H.R.1887.ENR, a federal law against depictions of animal cruelty. The FBI found that no animals had been harmed.
On April 8th, 2004, the graphic art website OmegaGrafix published a page featuring a satirical Bonsai Kitten Christmas ornament (shown below, left). On January 23rd, 2006, the image manipulation website Worth 1000 held a contest for members to create photoshopped examples of urban legends, with the winning image referencing the Bonsai Kitten hoax (shown below, right).
On August 15th, 2008, the YTMND site Kitten in a jar! was created by user isamiracle, which featured several Bonsai Kitten images in the background. Shortly after, other YTMND sites were launched referencing the hoax, including Bonsai Babies!, Square Melons vs. Bonsai, bonsai cats and Bonsai Homestar.
On January 14th, 2010, the YouTube channel for the website Rathergood uploaded a video for the song "The Internet is Made of Cats", which referenced the hoax (0:45 below).
 Wayback Machine – Cruel Site of the Day – Happiness is a Rectilinear Kitten