Harley Quinn is a sales juggernaut at DC Comics. Her main ongoing title is regularly one of the publisher’s top sellers, and her spin-off series, Harley’s Black Book, debuted as the eighth-best-selling book of December. Comparisons have been made between Harley and Marvel’s hit character Deadpool,
Source: Harley Quinn #25 features a breakthrough for DC’s hit character · Comics Panel · The A.V. Club
Super Secret Comic Book Club 