A Perfect Circle (often referred to as APC) was an alternative rock band, formed by guitarist Billy Howerdel. Howerdel had worked as a guitar tech for bands such as Nine Inch Nails, The Smashing Pumpkins, Fishbone and Tool. He played demos of his music to Tool's singer, Maynard James Keenan, who offered himself as vocalist should Howerdel ever form a band. Howerdel was initially hesitant about this as he originally wanted a female vocalist, but eventually agreed and A Perfect Circle was formed in 1999. To distinguish himself from his persona with Tool, Keenan wore long wigs on his otherwise bald scalp for all of A Perfect Circle's music videos, photo shoots and live performances.
The name phrase A Perfect Circle originated during the Middle Ages, when musical notation development was in the hands of the monks who inevitably associated religious and musical phenomena. To them the three-part concept of the Holy Trinity represented religious perfection; therefore to them only triple meter was perfect meter. To express this meter they placed the geometrically perfect circle at the beginning of the plainchant. Another interpretation is that they took their name from the line "Pull me into your perfect circle," from the song "Orestes", on the CD Mer de Noms. However, all the above theories have been refuted, as Maynard when asked at a public conference, stated that the name " A Perfect Circle" originates from the friendships of the band members, all of them met one of another in a way resembling "a perfect circle of friendship."
Taken from Wikipedia