There are at least 8 bands with this name. Note: There also is a French rock band with the same name but different spelling - Bästard.)
1. A short lived but legendary crust punk / d-beat band from Japan.
2. Death metal band based in Iceland.
3. An alternative rock band from Argentina formerly known as Blood Thirsty Bastards.
4. A short lived visual kei band, also from Japan.
5. And there is a band with the same name from Stord, a city located at the west-coast of Norway.
6. Bastard is also a drum and bass/breakcore artist from Romania.
7. Thrashcore band from Prievidza, Slovakia (RIP)
8. Alternative Rock/Pop band founded in Eskilstuna, Södermanland, Sweden by Jessicka Strandell (Play Dough) in 1997. There are still some tracks available on their garageband.com profile.
9. Czech hardcore (NS hatecore) project of singer from Ecce Mors
10. Malaysian experimental rapper