There are multiple artists with this name:

1) Black Metal band from Russia.
2) Psychedelic folk rock band from the UK.
3) A Doujinshi Circle from Japan.
4) A Hip-Hop artist from the USA.
5) Bläck Metäl band from the Czech Republic.
6) Alternative rock band from Cambridge, UK. 1) Forest is a black metal band born in 1994 as a project of Kaldrad (Branikald) and Dagorath, the leader of another horde from Blazebirth Hall called Rundagor (long dead now).

Read more about Forest on Last.fm.