Carnage

In the case of Carnage (first appearance 1991), in order for a faithful adaptation of the character to be introduced to the Marvel Cinematic Universe, Venom would have to be introduced first (he’s essentially Venom’s “son”, as the symbiote which created Carnage is the offspring of the Venom symbiote). That being said, would anybody mind? The Spider-Man 3 version of Venom was awful and Spider-Man fans would love to see a better live action portrayal of the character to make amends for the first one.

But anyway, Carnage is Cletus Kasady - a psychopath and homicidal sadist whose “colourful” history includes killing his own grandmother, attempting to kill his own mother and torturing and killing his family pet dog as a child. He grew up to become a serial killer and spent time in jail – sharing a cell with Eddie Brock, whose symbiote returned to bond with him, leaving behind an offspring that bonded with Kasady.

He became Carnage – essentially a more powerful version of Venom in every respect. His strength and speed was vastly superior, but he could also shapeshift his body. This allowed him to create sharp weapons that he had no hesitation in using, create other appendages like wings and camouflage himself in various ways.

His red colouring makes him more visually stunning than Venom as his superior power would make him one hell of an on-screen threat for the MCU’s Spider-Man.