Actor Nathan Fillion has been cast in a mystery role in James Gunn's Suicide Squad. 1 / 9
Fillion is the star of ABC's police drama The Rookie. 2 / 9
Before that, Fillion played mystery novelist Richard Castle for eight seasons on ABC's Castle. 3 / 9
Fillion and Gunn are friends and have worked together before on other projects. 4 / 9
Fillion cameoed as The Holy Avenger in Gunn's superheroic dark comedy Super, 5 / 9
Fillion is no stranger to superheroes, playing Captain Hammer in Doctor Horrible's Sing-Along Blog. 6 / 9
Fillion also voiced Green Lantern Hal Jordan in several DC Comics animated movies. 7 / 9
Fillion has expressed interest in the past in playing the time-traveling superhero Booster Gold. 8 / 9
Despite this, it is still unclear who Fillion might play in The Suicide Squad. 9 / 9