Yeth, Hound of Pestilence is a unique Hellion found in the Road to Alcarnus in Act II of Diablo III.
In combat, it has Desecrator, Plagued and Vortex traits.
A bounty may be offered to kill Yeth, in which case the secondary objective is to kill 50 enemies. While the objective says these additional enemies must be killed in Alcanus, those killed on the Road to Alcarnus count as well.