Maureen Ryan of The Chicago Tribune disclosed in her October 9, 2009 review of fifth season episode "Fallen Idols" that "the ubiquitous and talented Mark Sheppard" had been cast as the "pivotal" demon character Crowley in the upcoming episode "Abandon All Hope.." [REF].
In an exclusive interview with Michael Ausiello on July 15, 2010, series creator Eric Kripke confirmed that Crowley would return in the show's sixth season [REF].