Tantei Opera Milky Holmes (探偵オペラ ミルキィホームズ, Tantei Opera Mirukii Hōmuzu) is a media franchise owned by the Japanese trading card game company Bushiroad. The first release was an Internet radio drama, released in December 2009. An anime adaptation by J.C.Staff aired between October 7, 2010 and December 23, 2010, with a special episode aired on August 26, 2011. The second anime season aired between January 5, 2012 and March 23, 2012 with another special aired on August 25, 2012. A third series, titled Futari wa Milky Holmes, will begin airing from July 13, 2013. Other media includes a manga adaptation serialized in Comp Ace from 2010; a visual novel PlayStation Portable game, released in Japan on December 16, 2010, with a sequel released in August 2012; a trading card game tie-in with Bushiroad's Weiß Schwarz; and a light novel series published by ASCII Media Works under their Dengeki Bunko label. Milky Holmes is also the name of a seiyū unit consisting of the series' four main voice actresses; Suzuko Mimori, Sora Tokui, Mikoi Sasaki and Izumi Kitta.

The series is a homage to the detective fiction genre, and the four female leads are named after famous fictional detectives: Sherlock Holmes, Nero Wolfe, Hercule Poirot and Cordelia Gray.