Vault Peons are lesser servants of Greed, found in The Vault in Diablo III. While larger and stronger Vault Sentries guard the Vaults, and agile and quick Treasure Goblins travel to other worlds to bring treasures, Peons are apparently performing daily duties, such as cleaning, sorting the loot, and construction.
Vault Peons fight (and are animated) exactly like Imps, except for they generally do not flee from battle. They attack in large numbers, but pose no threat to the Nephalem, as their Life and damage are minimal. However, they can serve as a cannon fodder for Sentries, giving those time to get into close combat while players are busy dispatching the horde of Peons.