Nathan Christopher 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 Officer John Nolan on The Rookie and is an executive producer on the show, as well as its spin-off series, The Rookie: Feds during its run, as well as being a producer on an upcoming spin-off, The Rookie: North.
Fillion has acted in traditionally distributed films such as Slither and Trucker, Internet-distributed films including Dr. Horrible's Sing-Along Blog, television soap operas, sitcoms, and theatre. His voice is featured in animation and video games, such as the Bungie games Halo 3, Halo 3: ODST, Halo: Reach, Destiny, and Destiny 2, along with the 343 Industries game Halo 5: Guardians and the television series M.O.D.O.K.