Stoner doom band from San Jose, California. They began in 1990, disbanded in 1998 and reunited in 2009 to play a few shows.
Holy Mountain and Dopesmoker are great albums and I would recommend them to anyone who wants great pieces of work from Sleep.
The song Dopesmoker from the album of the same name is so amazing.
Snowblind is a great Black Sabbath cover.