The Empire is the only known name of the major human civilization in the Torchlight universe. Of the character classes, the Alchemist, Vanquisher, Embermage, and Engineer are all said to work for the Empire, which is in the process of colonizing the continent of Vilderan. The humans of the Empire consider Vilderan to be the "New World," with their as-yet-unidentified home continent presumably being the "Old World." However, human civilization is quite young compared to the empires of the past, such as those of the dwarves, Estherians and Zeraphi.
According to Runic's Jason Beck, Embermages are analogous to the soldiers of the Empire, while Vanquishers are akin to their "CIA/Secret Service/SEAL team." Similarly Engineers serve their aforementioned role keeping Ember powered machines in check whilst Alchemists act as the scientists of human civilization