Professional ratings
Aggregate scores
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Metacritic	62/100
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Source	Rating
411Mania.com
Allmusic
The A.V. Club	C−
Kerrang!
Metal Hammer
Rock Sound
Sputnikmusic
USA Today

Nightmare is the fifth studio album by American heavy metal band Avenged Sevenfold. It was released on July 27, 2010 through Warner Bros. Records. It was produced by Mike Elizondo and mixed in New York City by noted engineer Andy Wallace.Nightmare is the first Avenged Sevenfold record without James "The Rev" Sullivan performing drums on all the songs due to his death in December 2009; however he did write parts that were used for the final recordings, making this the last album he would write on, The Rev's vocals are still on the album as a tribute to him. This is the only album to feature ex-Dream Theater drummer Mike Portnoy, who performed as the drummer for the album in his place, also played with the band for all their tours through the end of 2010, due to his separation with Dream Theater. They then hired drummer Arin Ilejay, who played with the band for the next four years. The album has been certified Gold by the RIAA in the United States. The album debuted at number 1 in the Billboard 200. As of May 2014 the album has sold 818,000 copies in the United States.

In late 2009, two years after Avenged Sevenfold released their self-titled album, and four years after they had issued their breakthrough studio set, 2005's City of Evil, the band started working on their next record, their "most personal and epic that will definitely take you on a very dark journey." Around late 2009, the band worked on the album's production until the death of their drummer.

On December 28, 2009 the body of James "The Rev" Sullivan was discovered inside his home. This incident made the band suspend work on the album for some time. In the later months, Mike Portnoy of Dream Theater (a major influence on The Rev and the rest of the band) agreed to finish recording the drum tracks for the album:

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