1. New Zealand metalcore band. The band changed their name in 2008 to Antagonist A.D. to avoid to confusion with other bands holding the same name. 2. Antagonist are a metalcore band from Whittier, California in the United States. In the rapidly changing and evolving world of heavy music, bands come and go faster than you can get a value meal at a fast food restaurant. Finding bands who are still slugging it out after a decade is a rare occurrence. What’s even more uncommon is finding a band who have recorded their most intense and career defining album 12 .