Crowley
From Super-wiki
Crowley is Lilith's right hand man and possible lover. At the end of season 3 Bela told Dean that she had given the Colt gun to Lilth when it is reveled in The Real Ghostbusters that in fact she gave it to Crowley, this was discovered after super fan Becky told Sam. Crowley gave the Colt to the Winchesters and asked them to kill Lucifer before Lucifer killed all the humans then the Demons.