Hireling

Hirelings are similar to followers in Diablo III in that they will follow the player around and assist in combat. Unlike followers, however, they cannot be equipped, cannot level up, and are considered hardcore. Hirelings are not meant to replace followers[1]. Hirelings are generally part of quests of various complexity, and are somewhat akin to smarter, more clingy versions of the wandering NPC Barbarians found in Act 5 of Diablo II.

The terminology of a hireling, and the ability to categorize them, gets a little hazy when asking whether or not NPCs as part of an escort quest are considered hirelings or not. This information has yet to be revealed, but the beta may bring updates on it.

Development

Not much is known about hirelings or how large a role they will play in Diablo III. Leonard Boyarsky spoke in more detail about their plans for Mercs and hirelings at Blizzcon 2008.

We have two different types of mercenaries now. As you saw in the demo, if you got the quest where you could rescue the adventurers or their leader, those guys are a low level and are just along for the quest, or are cannon fodder. You can't really control them or have anything to do with them at all. When you have what we are calling followers, they are the guys you can equip, give them different weapons, you can give them different armor. They will probably have some quests that involve them. Much more than in Diablo II, you could equip them but they were more like a game mechanic in a body of an NPC. Where this time, were making them much more individuals with their own back story and their own reason for being in the world.

Known NPC Followers

Players have found various NPC hirelings in the playable demos at Blizzcon in 2008, 2009, and 2010. Hirelings are usually part of various scripted events and quests. In the known examples players found NPC warriors who needed assistance fighting off large groups of monsters, explorers who needed help reaching a special treasure, injured humans who requested escorts, and even an NPC merchant who felt his honor had been insulted by another NPC, and offered to sell his items at a discount if his reputation was restored.

With so many NPC follower events and mini-quests in the three playable demos so far, it seems very likely we'll see quite a number of these adventures and events in the final game.

A few examples:

The Barbarian finds Deckard Cain with three NPC archers in the dungeon in the WWI gameplay movie. The Barbarian orders Cain to follow him to safety, and the Archers come along to assist. They join in the battle and do their best, but are picked off one by one until only the Barbarian and Cain reach the end of the level.

The Escort Mission was a mini-quest in the Blizzcon 2008 demo. Players found an NPC guard captain who asked for assistance in locating the rest of his soldiers, as they'd become separated in battle. The Captain accompanied you as you explored the surrounding areas, and as each of his lost soldiers were found, they joined in as well, acting as durable, but low-damage, tanks.

Other such events were part of the 2009 and 2010 demo as well.

NPCs assist the Barbarian to rescue Cain.