A boss is a powerful enemy fought at the end of missions in the Azure Striker Gunvolt series.
In the first game, they are usually high-ranking members of the Sumeragi Group in charge of their respective areas, with a couple exceptions. Bosses are distinguishable from normal enemies in that their health is displayed at the bottom of the screen and in that the background music changes during the fights with them. Each boss also has a unique special move that they will use towards the end of the fight.
In Azure Striker Gunvolt 2, the majority of the bosses are members of The Seven, a group of powerful adepts within the multinational adept union Eden. Like the previous game's bosses, The Seven have much more health and power than regular enemies, and each have their own unique special moves.