Nathan Fillion Richard Castle Actor Stana Katic NYPD Captain Kate Beckett Actor Susan Sullivan Martha Rodgers Actor Molly C. Quinn Alexis Castle Actor Ruben Santiago-Hudson Captain Roy Montgomery Actor Tamala Jones Lanie Parish Actor Jon Huertas NYPD Detective Javier Esposito Actor Seamus Dever NYPD Detective Kevin Ryan Actor Robert Curtis Brown Ian Busch Guest Star Anne Ramsay Bree Busch Guest Star Erin Foster Sky Blue Guest Star Arye Gross M.E. Sidney Perlmutter Guest Star Clayton Rohner John McGinnis Guest Star Jesse Head Zack Metzger Guest Star Bernardo De Paula Franco Marquez Guest Star Andrew W. Marlowe Executive Producer Armyan Bernstein Executive Producer Barry Schindel Executive Producer Rob Bowman Executive Producer, Director Laurie Zaks Executive Producer Jose Molina Writer