United Abominations is the eleventh studio album by American thrash metal band Megadeth. Released on May 15, 2007, United Abominations is the first Megadeth release distributed through Roadrunner Records and, with the exception of the band's frontman Dave Mustaine, was recorded with an all-new line-up. It is the first album since The World Needs a Hero (2001) to be recorded by a full-time line-up as the previous studio album The System Has Failed (2004) was recorded by Mustaine alongside session musicians. While touring to promote the album, guitarist Glen Drover left the band for personal reasons and was replaced by Chris Broderick, leaving this as the only Megadeth studio album to which he contributed.

United Abominations was well received by critics and debuted at number eight on the Billboard 200, the highest chart position for the band since 1994's Youthanasia until it was succeeded by 2013's Super Collider. Greg Prato of AllMusic stated Megadeth "sound reborn" on United Abominations. The lyrics of the album deal with politics and the state the world is in, with Ed Thompson of IGN stating the album is the band's most politically charged. The album was named the number one metal album of 2007 by Guitar World. In the 2007 Burrn! magazine Reader's Poll, it was voted Best Album Cover, and "Washington Is Next!" was voted Best Tune.

Prior to the release of United Abominations, Megadeth signed a recording contract with Roadrunner Records. The band had troubles with music rights involving two former labels that carried Megadeth, Capitol and Sanctuary Records. This is the first Megadeth album since the 2004 album The System Has Failed, which was released through Sanctuary. While on tour to support The System Has Failed, Megadeth frontman, guitarist, and vocalist Dave Mustaine contemplated breaking up Megadeth to record as a solo artist. At a sold-out concert in Buenos Aires, Mustaine stated the band would stay together. The show in Buenos Aires, at which this information was announced, was recorded and released on CD and DVD as That One Night: Live in Buenos Aires.

Megadeth had a new band lineup, aside from Mustaine, comprising Glen Drover (guitar), James LoMenzo (bass guitar), and Shawn Drover (drums). Mustaine chose these people for full-time members rather than session musicians. He stated that he liked the Drovers' "sibling chemistry" and that LoMenzo was a "legend".

Mustaine stated he did not "go into making this record with any pre-conceived notions". He said some of the lyrics on United Abominations were written about his frustration with his past record labels, stating "a lot of that translated into the intensity on the record." Mustaine wrote the songs for the album in an attempt to "stir something in the minds of the listener". The lyrics of the album were mostly about choices the American government were making at the time, which Mustaine found to be foolish. Mustaine stated recording the new songs was "super fun", despite having troubles with some of the complex music and vocal arrangements. All of the lyrics and music, with the exception of one song, were written by Mustaine. "Never Walk Alone... A Call to Arms" was co-written by Mustaine and guitarist Glen Drover. When bassist James LoMenzo was asked about the lyrics of the album, he said to "talk to Dave about that". Although most of the band had no writing credits on the album, they stated that they were excited about recording the music.

United Abominations was recorded in 2006 at SARM Hook End Studios, London, England; the Steakhouse, Studio City, California; Big Fish Encinitas, California and Backstage Productions. Additional overdubs were recorded at S.I.R. rehearsal studio, Hollywood, California and Mustaine Music, Fallbrook, California. Most of the record was tracked in England because Mustaine admired the fact that his favorite band, Led Zeppelin, previously recorded there many times. Mustaine produced the album, with additional production handled by Jeff Balding and Andy Sneap.

"À Tout le Monde (Set Me Free)", is a remake of "A Tout le Monde" which originally appeared on the 1994 album Youthanasia. The song is a more uptempo version of the original song, and features Lacuna Coil vocalist Cristina Scabbia singing backing vocals. Scabbia stated she was "really surprised about it because 'A Tout le Monde' is a song that I've always loved. It was a big surprise for me to get this invitation—I was really honored to be part of it." Mustaine chose Scabbia over three other choices because of her "reign in the heavy metal business". Mustaine later stated that he originally intended for the song to be a B-side for Japan, but the president of Roadrunner Records (Megadeth's label for this release) wanted "À Tout le Monde (Set Me Free)" released as the album's first single.

"Amerikhastan" is about "immigration and fighting in between religions". Mustaine said the song was "basically (a) part 2 to 'Holy Wars'."