The Collector is a supervillain.
The Collector is part of a race of creatures born in the Big Bang. He serves a purpose like all his brothers and sisters, and the Collector's purpose is to collect the many lifeforms before great extinction events.
The Collector was first met in present time when he abducted many species and thousands of important people, including the Avengers and former Avengers Captain America and Black Panther. An upside of this abduction is that the Collector "cleansed" the subjects by curing Black Panther's wounded knee and Dr Richard Hawkins' paralysis. Then he dropped them in a jungle habitat from where they escaped with the help of Moon-Boy and Devil Dinosaur. Once outside, the Avengers past and present face the Collector and defeat him with a combination of Vision's solar blast and Scarlet Witch's hex power. The Collector then reveals they actually destroyed a construct, but decides to put all humans that wish to return on a ship back to Earth, to prevent further destruction of his collection.
The Collector only appeared in the comic book tie-in to The Avengers: United They Stand, but not in any series.
In the Comics
His name is Taneleer Tivan.
He collects rare species for his own amusement.