Xasthur /zæstər/ was an American black metal project that was founded by and consisted of Scott Conner, who goes by the pseudonym "Malefic". Although similar in terms of low-fi production and the wearing of corpse paint, musically and lyrically Xasthur's focus is usually not on paganism, Satanism or anti-Christian blasphemy – as is common in the genre – but rather on astral projection, darkness, despair, suicide, hate, and death.

Malefic has toured with Sunn O))) and has joined Nachtmystium on stage, but stated in an interview for Pitchfork Media that he "will always keep Xasthur a band that will not play live".