MODOK (Mental Organism Designed Only for Killing) is a mutagenically altered antagonistic technician of A.I.M. with superior intelligence. MODOK is the supream leader of the current A.I.M. and former leader of the Cabal in Avengers Assemble.
MODOK looks highly toward himself, priding his high intelligence. He has low regard for the weak-minded and treats the greater minds with disdain. When cooperating with genius like himself, he will only work with them to serve his own ends.
In this show, MODOK's acronym is MODOC, with the 'C' standing for "Conquest". MODOC is the leader of Advanced Idea Mechanics, a terrorist organization. He took part in the experiment that transformed Simon Williams into the Wonder Man.
Later on in the series, A.I.M. starts a war against Hydra when they realized the Cosmic Cube they created for them was more powerful than expected. When the Cosmic Cube is just finished, a Hydra ship attacks A.I.M.'s, MODOC fights Hydra leader Baron Strucker, and is defeated by Hydra's Dreadnoughts.
In the episode "Beetle Mania", when several of Beetle's felonies are shown, one of the scenes shown is Beetle freeing MODOK from prison. His only major role took place in "Contest of Champions (Part 3)" where he is a prisoner of the Grandmaster.
MODOK appears as an ally of Red Skull in in "The Avengers Initiative" where he helps Red Skull by disabling Iron Man and capturing Captain America at the Statue of Liberty. While in a HYDRA Base in Antarctica, MODOK operated a machine that would swap Red Skull's mind with Captain America's but the Avengers invaded the base and undid the body swap. MODOK gets away with Red Skull who swipes Iron Man's armor. When the Avengers regroup at Avengers Mansion, MODOK uses microbots to control the bodies of Captain America, Black Widow, Falcon, Hawkeye, Hulk, and Thor while Red Skull targets the Arc Reactor in Avengers Mansion. Iron Man figures out how the microbots work and frees everyone from the microbots control leaving Hulk to beat up MODOK. MODOK gets away with Red Skull after Hulk, Thor, and Falcon sent the detonating Arc Reactor higher in the sky so that it wouldn't destroy Manhattan. On Red Skull's submarine, MODOK witnesses Red Skull sending a message to every supervillain to join his Cabal in a plan to destroy the Avengers.
MODOK appears as one of the villains in the special.
Marvel vs. Capcom series
MODOK appears as a playable character in the Capcom crossover fighting game Marvel vs. Capcom 3: Fate of Two Worlds, and also makes a cameo in the background of a playable stage in Marvel vs. Capcom: Infinite.