640px-Symbiote invasion
The Symbiotes are a race of parasitic alien beings featured in the Marvel comics. They are goo-like creatures that attach themselves to a living host and feed off the negative energy (hate, greed, pride, etc) they make to grow stronger.

History Edit

The first appearance of the symbiote was in Marvel's Secret Wars comic line, in which the alien suit bonded to Spider-man, granting him greater power. After awhile, Spider-man learned that the suit was alive and taking over his life, so he had it removed a few times, as it kept coming back to him.

Eventually the symbiote found another host: frustrated, angry newspaper reporter Eddie Brock. The symbiote bonded with him, and together they became the super-villain known as Venom, who had the same powers as Spider-man, but stronger. Because the symbiote and Spider-man were allies for so long, Spider-man spider sense never registers Venom as a threat, making him even more dangerous. The symbiote-infected human always referred to themselves in the plural first person, saying "We" instead of "I".
Symbiote movie

The alien symbiote as it appears in Spider-man 3.