Season 5 introduces the demon Crowley, played by Mark Sheppard, who would become the Winchester's longest-recurring antagonist and occasional anti-hero in the series. Crowley appears in three episodes of season 5 to help the Winchesters seal Lucifer back in the Cage, believing that once he destroys humanity he will target all demonkind next. In season 6, Crowley becomes the King of Hell and one of the main antagonists working with Castiel to stop Archangel Raphael, the other main antagonist of season 6, from restarting the Apocalypse by harnessing the souls of Purgatory and splitting the power with Castiel. In season 7, Crowley becomes an anti-hero who helps the Winchesters against the threat of Leviathans led by Dick Roman, after they are released from Purgatory by Castiel. Crowley becomes the main antagonist of season 8, attempting to harness the Words of God and their powers and stop the Winchesters from sealing Hell forever. In season 9, Crowley becomes an unwilling prisoner of the Winchesters but is forced to deal with Abaddon trying to steal his position as King of Hell. Sheppard was promoted to series regular status for season 10.