Hound of UIster wrote:
The Sony Spectacular Spider-Man cartoon couldn't use Kingpin and according to the producers, it was because the Spider-man contract that Sony had didn't have the rights to him.
That's television rights though, and may have been covered under a different contract. That show ended before the television rights reverted back to Marvel. I believe Marvel has exclusive television rights to all characters at this point.
This includes live-action, meaning technically Spider-Man could appear on Agents of SHIELD, but Sony still owns the likeness and appearance of Spider-Man, so they'd have to work around that. Marvel's better off leaving it alone.