I really discovered Pantera as late as in late 90's/early 2000. But it didn't take me long to know that Pantera was/is one of the most important bands of heavy metal genre.
Pantera's earliest albums (the before Cowboys From Hell -era) were somewhat uninteresting and pretty bland. But when Philip Anselmo joined and they added new kinda grooves to their sound, it was a kick in the ass that metal music needed at that time. The genre was spoiled by all the cheesy hair metal bands and their endless copycats. Rock and metal scene would be totally different if it wasn't for Guns N' Roses and Pantera.
Sadly they broke up in rather nasty way and more sadly one of the greatest guitar players of all time…