Poison is a symbiote produced by Venom. Poison didn't last long because he couldn't find a host and he eventually died off. But he rose again and found a host.
His host was named Drew Faca. Drew was a scientist working for Nasa and was turned into Poison. He eventually adapted to the loud noises and got on a space ship and tried ruling the universe, but was killed by Captain Marvel
Poison's name comes from his color, because his color is the color of a high rated poison that can kill you. That poison is not apart of the real world (I hope).