Venom, or the Venom Symbiote, is the name given to the first symbiote life form to appear in the fictional Marvel Universe. The creature is a sentient alien with a liquid-like form. It requires a host, usually human, to bond around for its survival. In return the Venom creature gives its host enhanced powers. In effect, when the Venom Symbiote bonds with a human to form a super-villain, that new dual-life form itself is also often called Venom. The symbiote, with or without a host, is an arch-enemy of Spider-Man, who was the first host it merged with before its evil motives were clear. After Spider-Man rejected it, the symbiote went on to merge with other hosts and so began its popular reign as the villain known as Venom.

The Venom Symbiote first appeared in Secret Wars vol.1, #8 where Spider-Man first encountered it and unwittingly merged together. After Spider-Man rejected it the Symbiote merged with Eddie Brock, its most well-known host, in The Amazing Spider-Man #299 (March 1988). Its current host is Mac Gargan, the villain formerly known as Scorpion.

Originally, the Venom symbiote was portrayed as a mute and lonely creature craving the company of a host. More recently, it has been shown as increasingly abusive of its hosts, and having the powers of speech. Also the Venom Symbiote itself has no known name, as Venom is essentially the moniker it has adopted since its history with Spider-Man on Earth. According to S.H.I.E.L.D., it is considered one of the greatest threats to humanity, alongside Magneto, Doctor Doom, and Red Skull.

The Venom symbiote also appears in the film Spider-Man 3 first merging to Spider-Man's suit and then to Eddie Brock.