I've only got two:

#Prong (thrash metal): They were far ahead of their time in blending punk and metal. Their 1993 album, "Cleansing", is one of my favourite heavy metal albums ever. Unfortunately, it was a case of the student out-performing the master as younger bands which followed their formula caught all the limelight. Prong are still soldiering on though, and are currently working on a new album.

#Diamond Head (NWOBHM): Excellent, blues-based, riff-heavy fantasy metal - think Deep Purple meets Motorhead, plus a sense of fun. Largely eclipsed by Iron Maiden and Saxon - superior bands, in my opinion, but nonetheless not quite the same. One of Metallica's best songs, "Am I Evil?", is a Diamond Head cover.