Dread Stalker

Dread Stalkers, Greater Terror Demons, are two Unique Terror Demons found in the Crumbling Bunker in of Diablo III. They spawn and attack together, although they count as separate monsters for killing purposes. They are not guaranteed to spawn. If they do, there is a chance they will guard a Cursed Chest.

In combat, they both have no affixes, but are very fast and have triple attack speed.

Trivia

 * In World of Warcraft: Legion, players of the warlock class can summon twin Dreadstalker demons to their aid.