Richard Edgar "Rick" Castle is a fictional character on the ABC crime series Castle. He is portrayed by Nathan Fillion.

Nathan Fillion is a Canadian and American actor. He played the leading roles of Captain Malcolm "Mal" Reynolds on Firefly and its film continuation Serenity, and Richard Castle on Castle. As of 2018, he stars as John Nolan on The Rookie and was an executive producer on the show as well as its spin-off series, The Rookie: Feds.