There are 3 bands that are/were called Black Widows:

1] An all-female Gothic Metal band from Portugal formed in 1995. They've released 1 EP ("Dark side of An Angel" in 2001) and 1 album ( "Sweet...the hell" in 2002)

2] A Louisville Ky hardcore band now known as Black Cross, which consists of ex-members of By The Grace Of God, Guilt, Endpoint, The National Acrobat and Automatic.

3] A Belgium all-female band from Ghent. Read more on Last.fm. User-contributed text is available under the Creative Commons By-SA License; additional terms may apply.