Sergei Kravinoff AKA Kraven the Hunter was a Russian big-game hunter who stole a potion from a jungle-priestess named Calypso which gave him the strength, speed, reflexes and endurance of a mighty jungle-cat. Eventually Kraven moved to New York in order to hunt Spiderman as he believed him to be the ultimate hunt. He was one of the original members of the Sinister Six.
In Ultimate Spider-Man
In the Ultimate Spider-Man TV series, Kraven the Hunter is the man who destroyed Hector Ayala, the father of Ava Ayala. Eventually, he found the whereabouts of White Tiger in New York. Spider-Man, while not being wanted by either side at that location, helped White Tiger defeat Kraven the Hunter. Eventually, Kraven stole White Tiger's amulet, making White Tiger herself go back to her usual behavior and turning Kraven into a humanoid white tiger, Ava losing her powers in the process. Eventually, Spider-Man and White Tiger defeated Kraven and regained the amulet.