Ultra

An Ultra (also known as Boss in Destiny 2) is the most powerful type of enemy in the Destiny series due to their high damage and health values. They can be identified by their large sizes and the way their health bar is displayed: shown as a giant yellow bar with a skull symbol in it (formerly as a skull next to the bar in Destiny.)

Gameplay
Ultras serve as bosses and are therefore meant to pose a challenge to Guardians. They appear in Story missions, Dungeons, Strikes, and Raids; rarely will they appear during Patrol, usually as part of a World Event. Ultras at the end of activities often have unique attacks, defenses, or mechanics related to their battle, generally increasing in number the more complex the activity is meant to be. All Ultra generally share the following characteristics:
 * Area-of-Effect Melee Attack
 * Heavy Ranged Attack (from their equipped weapon)
 * Summon Reinforcements
 * Rapid Movement
 * Immunity to Blinding, Suppression, Suspending, and Freezing
 * Immunity to Finishers

List of appearances

 * Destiny
 * Destiny 2