Black One is the fifth studio album by American drone metal band Sunn O))). As the title implies, the album is very black metal-influenced, utilizing many guest musicians of the genre, including Malefic and Wrest from Xasthur and Leviathan, respectively. Malefic, a sufferer of claustrophobia, was allegedly locked in a casket during his recorded performance to the vocals on the track "Báthory Erzsébet".