Diablo III is set to include three variations of AI controlled partners that accompany you throughout the main game. Similar to the mercenaries from Diablo II, the follower system in Diablo III is broken into three distinct groups. The AI companions are Kormac the Templar, Eirena the Enchantress, and Lyndon the Scoundrel. Each will have their own sets of skills to assist in the game. Kormac is a melee unit with specs that can be altered to different roles. Eirena can cast buffs or deal long range damage. Lyndon will also deal ranged damage but is said to be a more damage focused unit with more attacking options. The three units will all feature their own story and introductory quests while players are learning to use these new followers.
Diablo III which is yet to be pigeon holed to a release date, is rumored to be arriving either late this year, or early in 2012. The Diablo III beta was just recently announced for Q3 2011 and could begin as early as July.