User blog comment:Rafe Adler/"The Scorpion and The Frog" Discussion/@comment-28192538-20171201033100/@comment-1031724-20171201044451

They killed Crowley coz Mark Sheppard wanted to leave the show (probably got tired of it). To bring him back they'd have to have someone else play him, and I don't think the fans would accept that after knowing and loving Mark Sheppard as Crowley in 8 seasons. That's why they brought back Mark Pellegrino for Lucifer.