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".

[9] 2,000 copies included a bonus disc titled Solstitium Fulminate, containing a mix of live performances recorded at Roskilde Festival in 2005 and the immediately preceding European tour.

"Báthory Erzsébet" was recorded as a tribute to Quorthon (as well as the countess who inspired Bathory's name) and, according to an interview with Terrorizer magazine, is loosely built "around a really slowed down riff from 'A Fine Day to Die'".