There is more than one artist with this name.
1) Formed in 1998 by Lloyd James and Joanne Owen. Often categorised as part of the 'neo-folk' genre, their songs also have similarities with acts such as Swans and Wire. Lloyd James of Naevus releases solo material under the name Retarder and is also a member of the groups Lark Blames and Man Eat Man Eat Man. Official Naevus facebook page: http://www.facebook.com/#!/pages/Naevus/22994751603
2) A German doom-metal band founded by guitarist and vocalist Uwe Groebel of Voodooshock fame. Formed in 1991 they first sounded like a slow death-metal band in the vein of Anathema / My Dying Bride / Asphyx, but over the years Naevus’ sound developed a doomer edge picking up influences from Black Sabbath and Cathedral. Naevus recorded three demos and finally in 1996 signed a deal with Lee Dorrians’ Rise Above Records in London, England. Naevus’ debut album, Sun Meditation, was recorded in 1997 and released in 1998. In 1999, they were let go from the label due to lack of funds and a change in distribution, so the band decided to split in May that year.