Casting Principale:. Penny Johnson Jerald: (Captain Victoria Gates), Nathan Fillion: (Richard Castle), Stana Katic: (Detective Kate Beckett), Jon Huertas: (Detective Javier Esposito), Seamus Dever: (Detective Kevin Ryan), Tamala Jones: (Lanie Parish), Molly C. Quinn: (Alexis Castle), Susan Sullivan: (Martha Rodger). Guest Cast:. Darby Stanchfield as Meredith, Stephanie Drapeau as Michelle Twohey, Brendan Ford as Walter Voss, Deji LaRay as Herman Poquille, Jack Wagner as Billy Piper, Nancy Lee Grahn as Samantha Voss, Mark Deklin as Corey Francis. Writer: Terence Paul Winter and Director: Holly Dale. Castle 5x10 Promo/Preview "Significant Others". Castle 5x10 "Significant Others" US Promo (HD). Castle Season 5 Episode 10 Sneak Peek. Castle Season 5 Episode 10 Promo. Castle S05E10 Promo/Sneak Peek. Castle S05E10 Sneak Peek. Castle Season 5.