U.D.O. is a German heavy metal band founded by lead singer Udo Dirkschneider in 1987.1987–1992After Udo Dirkschneider left Accept in 1987, a large fan community followed him to U.D.O.Starting with the first albums Animal House in 1987 and Mean Machine in 1988 U.D.O. proved to be pure heavy metal without any Trend-Sound influences. Both albums continued where Accept had left off in 1986 with Russian Roulette. Apart from Udo, Animal House was recorded by Peter Szigeti (guitars), Frank Rittel from Warlock on (bass), Mathias Dieth from Sinner and Gravestone (guitars) and Thomas Franke (drums).From 1987 - 1989 they toured with the following line-up: Udo Dirkschneider (vocals), Mathias Dieth (guitar), Andy Susemihl (guitar), Dieter Rubach (bass) and Thomas Franke (drums). They toured with Guns N' Roses, Lita Ford and Zodiac Mindwarp.By Mean Machine (released in 1988) the band had a different line-up: only Udo, Mathias Dieth and Andy Susemihl remained. New additions were Thomas Smuszynski (bass) and Stefan Schwarzmann (drums).U.D.O. achieved success with the album Faceless World, produced by ex-Accept drummer Stefan Kaufmann. U.D.O.'s follow-up album was Timebomb, and it was their last for five years.1996–presentFrom 1992-1996 Accept reformed their classic line up, and Dirkschneider put U.D.O. on hiatus to record three albums with his old Accept colleagues. After another break up, Dirkschneider returned to U.D.O., with Stefan Kaufmann (guitar), Jürgen Graf (guitars), Fitty Wienhold (bass) and Stefan Schwarzmann (drums). Udo Dirkschneider and Stefan Kaufmann then recorded tracks for the Tribute to Judas Priest compilation of Judas Priest cover songs, U.D.O. performing the track "Metal Gods".1997 saw the band return with Solid, the first full-length U.D.O. album to feature the guitar work of Stefan Kaufmann. Solid featured on the Rock Hard magazine reader charts for more than a year after release.Solid was followed by No Limits in 1998, and featured a similar songwriting approach as the previous year's effort. The album also featured U.D.O.'s first returning lineup since the band's inception ten years prior. The album also featured a cover of the Austrian pop band Supermax's hit single "Love Machine".With the release of the critically acclaimed Holy a return to the guitar-driven sound similar to Balls to the Wall-era Accept. A world tour followed with dates in the United States and several other major countries. Lineup changes occurred during the second part of the 1999 tour with Igor Gianola, ex of Gotthard, replacing Jürgen Graf. When the No Limits tour concluded, Schwarzmann quit the band, and on the Holy tour (2000) Lorenzo Milani took his place behind the drum kit. The tour also spawned U.D.O.'s first live album, Live from Russia a two-disc affair which featured many of the classic Accept tunes (with the exception of "Balls to the Wall") that have since become staples of U.D.O.'s set.2002's Man and Machine received a somewhat lukewarm response. Despite standout songs like the title track and "Private Eye", the album was ultimately less successful than its predecessor. It is notable for spawning a promo video of "Dancing With An Angel", featuring a duet between Udo and Doro Pesch (of Warlock).The next two studio releases – 2004's Thunderball and 2005's Mission No. X – were slightly livelier affairs, with the band's touring of Germany, South America, and Eastern Europe. Sonically, the former shared much in common with Timebomb, while the latter followed No Limits.It was with 2007's Mastercutor, that U.D.O. returned to form. The album was the most financially successful in years and received universally high marks from musical critics and metal fans alike. Udo's appearance on Finnish metal band Lordi's album, The Arockalypse, exposed U.D.O. to a wider audience. Live DVD Mastercutor Alive was released in 2008.U.D.O.'s twelfth studio album, Dominator, was released on 21 August 2009. U.D.O.'s next studio album, Rev-Raptor was released on 20 May 2011.On 12 September 2012 Stefan Kaufmann, longtime guitar player in U.D.O. has left the band for health reasons. The band has begun with the preparations for the forthcoming studio album and is looking for a guitar player with immediate effect. Stefan will continue to work in the surroundings of the band and produce bands in his own ROXX studio. Steelhammer was released on 20 May 2013.