Venom

The character, the brain child of David Michelinie, Mike Zeck and the legendary Todd McFarlane, made its first appearance in the Amazing Spider-Man in 1984.
Seeking out a way to repair his suit which has been damaged during a savage battle, Spider-Man stumbles across the creature and it bonds with him, instantly forming a new suit.
But Spider-Man discovers that the substance is actually a sentient being, and that it wants to bond with him permanently.
With the help of Mr Fantastic and the Human Torch, Spider-Man removes the symbiote and locks it away in a cell.
But the creature escapes and hides in Peter Parker's closet disguised as a suit, and when Parker puts it on the symbiote tries to forcibly bond with Spider-Man.
One again Spidey has to fight to remove it and fights his way to a church bell tower, were the loud ringing of the bells helps our hero to force the symbiote out.
Bitter and rejected, the substance takes over journalist Eddie Brock and Venom is born.
Through a mutual loathing of Spider-Man Brock/Venom declares all out war on out hero and the pair are locked in deadly battle on several occasions.
But there is also a good streak in Venom, which often drives him to protect the innocent - even if it means joining forces with his bitter enemy.
During various story lines Venom has bonded with other characters, most notably Mac Gargan, the villain formerly known as Scorpion and his current host.
The symbiote approached Gargan, offering him new powers and the ability to finally kill Spider-Man.
A fierce battle ensues and finally, broken and defeated - Venom slips away.
There have been many versions of Venom, with the character appearing both in the Ultimate Marvel Universe and Marvel Mangaverse. There was also a Venom 2099 - a futuristic re-imagining of the character.