Malevolent Tormentor

The Malevolent Tormentor, Spiteful Sprite is a variant of the Treasure Goblin in Diablo III, introduced patch 2.1.2. They have greatly increased chances to drop Legendary Items when killed, scaling with difficulty, up to the point where they are guaranteed to drop those, or even drop more than one. Visually, they have shining bronze appearance.

As a possible reference to their name, these Goblins can teleport at will, making catching them especially challenging, even more so when surrounded by other monsters.