Dire troll

Dire trolls are a small number of trolls that are strikingly larger and more heavily muscled than the rest of their brethren. They are very rare, and found deep in troll territories such as the Sunken Temple and Zul'Gurub. There is no racial distinction between them and the rest of the troll race. A variety of reasons might be behind this unusual size and musculature. For example, dire trolls might have been altered alchemically or magically through curse or enchantment. They might also simply have been born larger than average. Regardless of the day-to-day prejudices that these trolls must contend with from other races, dire trolls are not regarded as monstrous by other trolls.

Dire trolls is a name used by outsiders of troll societies, it's unknown exactly what trolls call them, other than just another troll.

In Wrath of the Lich King
The Scourge is producing dire trolls called "Blightbloods" by blighting Drakkari trolls with crystallized Blight. However, the Blightbloods were never deployed because players stopped Drakuru's intentions.

Trivia

 * Many dire trolls have eyebrows, a trait not often seen in trolls.