Nightmare is the fifth studio album by American heavy metal band Avenged Sevenfold, released on July 23, 2010, through Warner Bros. Records. It was produced by Mike Elizondo, mixed in New York City by audio engineer Andy Wallace, and mastered by Ted Jensen.

Nightmare is Avenged Sevenfold's first album to be recorded without Jimmy "The Rev" Sullivan performing drums 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 and his vocal takes are still on the album as a tribute to him. The rest of the drum tracks were handled by Dream Theater drummer Mike Portnoy, who also played with the band for all their tours through the end of 2010. They then hired drummer Arin Ilejay, who played with the band from 2011 to 2015.