Kraven the Hunter
A famous big game hunter who became a mercenary and later developed an intense obsession with restoring honor to his name, Sergei Kravinoff, also known as Kraven the Hunter, has been known as a major threat for Spider-Man and as a founding member of Oscorp Industries' premiere superhuman team - The Sinister Six.
Unbestknowen to all except for Gustav Fiers and Alexander Pierce, Kraven was once approached by the enigmatic Arnim Zola during the 60's to serve as a member of S.H.I.E.L.D.'s original Secret Avenger Initiative as part of HYDRA's plans to form their first attempt at a superhuman team to control the world. Kraven has since gone on to become a Cross-Species himself by injecting a combination of lion, leopard, and cheetah DNA into his bloodstream thanks to Oscorp's experiements.