Sven Erik Kristiansen (born 4 February 1969) is a Norwegian musician, best known as the former vocalist in the black metal band Mayhem under the stage name Maniac.

When Hellhammer decided to revive Mayhem in 1994 after the deaths of both Euronymous and Dead, and the imprisonment of Count Grishnakh, he invited Kristiansen to return as the band's vocalist.

[2] However, in a later interview Kristiansen stated when the band realized that the cutting had become a phenomenon people came to watch, he quit doing it.

[2] Kristiansen left Mayhem in 2004 through mutual consent due to his drinking problem and lack of time off.

According to him, the turning point for becoming sober was finding himself hanging by one arm out of a fourth floor window with no recollection of how he got there.