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 Paul Schackman Barry Guest Star Gil McKinney Tyler Benton Guest Star Amy Gumenick Danielle Guest Star Mark Damon Espinoza Professor Stevenson Guest Star Keiko Agena Kelly Guest Star Devon Gummersall Matt Haley Guest Star Tom Schanley William Carraway Guest Star Azita Ghanizada Mistress Sapphire Guest Star Andrew W. Marlowe Executive Producer Armyan Bernstein Executive Producer Barry Schindel Executive Producer Rob Bowman Executive Producer, Director Laurie Zaks Executive Producer Kate Sargeant Writer