Operation B.E.S.T. (Best Elite Secret Training) is an old online MMORPG style game on the Cartoon Network Website, created in 2004 and brought down in November of 2005. The contest lasted from October 29, to December 17, 2004, but the game remained playable into the next year.

This game's purpose was for the player to create their own KND Operative to take on missions as a member of Sector V to gain points for a high score. Over 1.4 million players registered throughout the duration of the event.