Stone Guardian

Stone Guardians are level 53 mobs found in Un'Goro Crater.

Background
They roughly patrol the river that flows from the southeast to the northwest of the Crater.

They are the only mobs that drop the Guardian Stones used in some crafting professions. The Guardians are flagged as non hostile and will not attack unless attacked. They are reasonably easy to kill as a well-geared level 60 because they move rather slowly, unlike the Devilsaurs that also inhabit the region.

Cataclysm
In World of Warcraft: Cataclysm, the Stone Guardians invaded Marshal's Refuge and established themselves there, killing Dadanga in the process.

Trivia

 * The Stone Guardians in Un'Goro Crater are carved with with the same sort of runes found on the Crystal Pylons and the pylons that guard the entrance to the crater..