MODOK stands for "Mental Organism Designed Only for Killing." He is a fictional supervillain in the Marvel Comics universe, created by writer Stan Lee and artist Jack Kirby. MODOK is known for his large head, small body, and advanced intelligence, which he uses to devise complex plans against superheroes, particularly Captain America and Iron Man. Originally a human named George Tarleton, MODOK was transformed by the A.I.M. organization into a powerful being with enhanced mental capabilities. His character often embodies themes of scientific experimentation and the consequences of unchecked ambition, making him a unique and memorable antagonist in the Marvel franchise.