From WoWWiki

There are a few bosses in Azeroth that can Frenzy. While frenzied their size, attack speed, and damage increase dramatically. However it can be removed by a Hunter using Tranquilizing Shot. Mobs that frenzy include Chromaggus, Magmadar, Flamegor, Maws, Princess Huhuran and Hakkar the Soulflayer when High Priest Thekal isn't killed.

Artorius the Doombringer and Klinfran the Crazed have a similar Demonic Frenzy ability that turns the mob red, increases spell and melee damage by 300% (four times as much damage), and removes all magic, poison, curse, and disease debuffs. This can be removed by Tranquilizing Shot, and can also be removed from Klinfran with Scorpid Sting.

Links

• Thottbot - Thottbot listing for frenzy