User blog comment:LucidPigeons/Category Cleanup/@comment-366087-20160301040504/@comment-34097347-20160306215401

So, in resume:


 * Big Bad/Main: The central/primary antagonist of the series as a whole
 * Major: Any important antagonist below the main one
 * Minor: Any other not-as-important villain
 * One-Shot: Villain with a single appearance
 * Bigger Bad/Greater Scope Villain: Villain above the main one, a driving force behind the whole plot, but has not as much screentime