Dr. Octagon is a persona created and used by American rapper Keith Matthew Thornton, better known as Kool Keith. First appearing on Thornton's 1996 debut solo album, Dr. Octagonecologyst, Dr. Octagon is an extraterrestrial time traveling gynecologist and surgeon from the planet Jupiter. Thornton performed and released two albums under the alias. The character was murdered by Dr. Dooom on Thornton's 1999 album First Come, First Served, and was briefly revived before once again being killed on Thornton's 2008 album Dr. Dooom 2, in response to the release of The Return of Dr. Octagon, an album largely produced without Thornton's involvement.

Thornton and KutMasta Kurt recorded two songs under the alias Dr. Octagon, Dr. Octagon and Technical Difficulties. Thornton mailed the songs to radio stations as a teaser, as well as giving copies to several DJs, as well as producer Dan The Automator Nakamura, resulting in the production of Dr. Octagonecologyst. The album was recorded in Automator's studio in the basement of his parents' San Francisco home. Dr. Octagonecologyst featured the work of turntablist DJ Qbert and additional production by KutMasta Kurt. An instrumental version of the album was released under the title Instrumentalyst (Octagon Beats). KutMasta Kurt later pursued legal action against Automator because Kurt's demos had initiated the project.

In 2002, Thornton announced The Resurrection of Dr. Octagon, a proposed sequel to Dr. Octagonecologyst, that would reintroduce the character. Los Angeles-based producer Fanatik J was chosen to create the music for the album. s production on the album was underway, Thornton had a falling out with Fanatik J over contract rights, and the One-Watt Sun production team was hired to create the album's music. After completing three vocal tracks with the label, based upon rough sonic themes created by the production team, Thornton had a falling out with the label, and gave the label recordings he had made two years previously, consisting of Thornton rapping and goofing off, in order to complete his contract. The resulting album, The Return of Dr. Octagon, was largely produced without Thornton's involvement, and did not resemble the direction Thornton had initially intended for the album.

As of 2017, a reunion of Keith, Automator and Q-Bert has been playing a host of live shows to coincide with the 21st anniversary of Dr. Octagonecologyst.