Valve has announced two characters coming to Dota 2: Pit Lord (renamed to Underlord), who appeared in the original Dota mod, and The Monkey King, a character who has never been playable before.
Pit Lord (Underlord) Preview Video
The Monkey King Preview Video
Pit Lord (Underlord) – release: End of this month.
The Monkey King – release: End of 2016.