Erebus very evidently served as one of the main inspirations for Tirek (aside from Tirac himself): Other than common tropes like being power hungry and betraying a henchman that is no longer useful to them, both start out very weak and cloaked, trick a good character into helping them get stronger, and as they get stronger (which both do via consuming shadows/magic through their mouths) they increase in size as well. And once they are defeated, all the power they stole is stripped away from them and the two are imprisoned instead of killed. Additionally, Tirek's horns in his later forms resemble Erebus' spiky eyebrows.