Dr. Carnage is the chief antagonist of the infamous comedy-horror film known as "Terror Toons" - a film often cited as being one of the worst modern movies of all time, however the film was never intended to be taken seriously and is an over-the-top farce in the style of a Troma film (that is focusing on "camp" humor, ultra-violence and slapstick comedy). Despite the comedy elements Dr. Carnage and his ape-like assistant, Max Assassin, are vicious and demonic killers who take great pride in slaughtering everyone they come across - it is also revealed near the end of the movie that both Dr. Carnage and Max Assassin are the creations of Satan himself, designed to aid him in conquering the world.
Dr. Carnage is a stereotypical mad scientist who proceeded to slaughter everyone in the home except the main protagonist, who eventually managed to kill him and Max Assassin - resulting in her parents returning home to find her laughing hysterically, surrounded by her dead friends (having presumably been driven insane by her ordeal).
In typical horror movie fashion the ending cuts to a new scene in which a little boy recieves a "Terror Toons" DVD and plays it in his bedroom, only for the door to slam shut by itself ominously.