Were you looking for The Warden, an NPC?
Warden is the name for Blizzard's anti-hacking program. It is installed with WarCraft III and World of WarCraft, and is planned to be included in StarCraft II and Diablo III.
The program uses a detection system on a player's RAM memory to detect any programs that are intended to modify or hack the game. There has been some debate of the functionality of the Warden, and if it transmits personal data, but most fans feel that the preventions of cheating and hacks is worth a lot.