Harley Quinn TV series has lined up a very exciting star for its third season, as fans continue to guess which character from James Gunn's The Suicide Squad will also be lending their voice. Following the news that a "very special guest star" will be joining the animated series, Harley Quinn co-showrunner Patrick Schumacker has also confirmed the involvement of Sam Richardson, who played Richard Splett in the political satire show Veep.