There are multiple artists with this name:

1) Wolf is a heavy metal band from Sweden (active).

Current line-up:
Niklas "Viper" Olsson – Lead Guitars & Vocals
Anders "Tornado" Modd – Bass
Richard "Raptor" Holmgren – Drums
Simon Johansson – Guitar

2) Wolf is a heavy/speed metal group from Japan (Currently disbanded). For this specific band, please change your tags to ＷＯＬＦ.

3) Wolf is a NWOBHM band from Cheshire, UK (disbanded).

4) Wolf is a NWOBHM band from Newcastle, UK. Previously known as Black Axe. (disbanded)

5) Wolf is a black metal outfit from Germany.

6) Wolf is the stagename of a demoscene musician, Maarten van Strien. He predominantly used the handle Wolf_ in his compositions on the MSX home computing platform before adopting the more widely known handle of Crystal Score. Songs on Last.fm have been tagged with crystal score to distinguish them from compositions of other artists named Wolf.

7) Wolf is also an italian singer-songwriter from Pisa.

8) Wolf is also a Jazz Rock/Fusion (progressive rock) artist originating from United Kingdom, also known as Darryl Way's Wolf

9) Wolf was a rac project of Ken McLellan & Kai Stüwe.

10) Wolf is also an Indie band from Belgium: http://www.myspace.com/wolfsamples

11) Wolf is also the nickname of an indie musician from argentina, that plays in lots of bands and solo projects ranging from prog jazz to delta blues and chiptune music.

12) Wolf are a black metal band from Mexico

13) WoLF is the nickname of Patrick Pinion, a downtempo/electronic artist hailing from the UK: http://wolf-music.bandcamp.com/releases