Nathan Fillion stars as mystery novelist Richard Castle, Stana Katic as Detective Kate Beckett, and Seamus Dever as Detective Kevin Ryan in Castle.
Main cast
- Richard CastleNathan Fillion1–8Main
- Kate BeckettStana Katic1–8Main
- Javier EspositoJon Huertas1–8Main
- Kevin RyanSeamus Dever1–8Main
- Lanie ParishTamala Jones1–8Main
- Roy MontgomeryRuben Santiago-Hudson1–3Main
- Victoria GatesPenny Johnson Jerald4–8Main
- Martha RodgersSusan Sullivan1–8Main
- Alexis CastleMolly Quinn1–8Main
Supporting cast
- Jim BeckettScott Paulin1–8Supp
- Ashley KennerScott Michael Foster1–2Supp
- Dr. Carter BurkeMichael Mosley1–2Supp
- Special Agent Jordan ShawDana Delany1–2Supp
- Ethan SlaughterAdam Baldwin3–4Supp
Guest & voice
- Terrance HodgesAl Sapienza1Guest
- Sidney PerlmutterArye Gross1–8Guest
- Maddy ‘Mack’ BristowErick Avari1Guest
- Molly PrestonMonet Mazur1Guest
- Agent ShawDana Delany2Guest
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About this cast
Castle is a light-hearted crime drama that follows Richard Castle, a bestselling mystery novelist, who shadows NYPD Homicide Detective Kate Beckett to research his next book. The series blends crime-solving with witty banter and a will-they-won’t-they romance between the leads.
FAQs
Who plays Richard Castle in Castle?
Richard Castle is played by Nathan Fillion.
Who plays Kate Beckett in Castle?
Kate Beckett is played by Stana Katic.
How many seasons of Castle are there?
Castle has 8 seasons, aired from 2009 to 2016.
Is Castle based on a true story?
No, Castle is a fictional television series, though the character of Richard Castle was inspired by author Richard Castle, a fictional persona created by ABC.
Why did Castle end?
Castle was cancelled after 8 seasons due to declining ratings and behind-the-scenes contract disputes, particularly with lead actress Stana Katic.
Sources & where to watch: IMDb · Wikipedia · Where to watch (JustWatch UK) · Updated June 2026