Nathan Fillion (born March 27, 1971) is a Canadian-American actor. He played the leading roles, Captain Malcolm "Mal" Reynolds on Firefly and its film continuation Serenity, and Richard Castle on Castle. Beginning in 2018, he has starred as Officer John Nolan on The Rookie. He is also an executive producer on the show, as well as its spin-off series, The Rookie: Feds. He is set to produce 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 and James Gunn's PG Porn, television soap operas, sitcoms, and theatre. His voice is featured in animation and video games, such as the Halo series games Halo 3, Halo 3: ODST, Halo: Reach, and Halo 5: Guardians, the Destiny series games Destiny, and Destiny 2, the television series M.O.D.O.K. (2021), and in the DC Universe Animated Original Movies as Hal Jordan / Green Lantern. He continued to portray Green Lantern in the DC Universe (DCU), this time as the incarnation of Guy Gardner, starring in the DCU film Superman (2025), and appearing in series Peacemaker (2025) and Lanterns (2026). Fillion first gained recognition for his work on One Life to Live in the contract role of Joey Buchanan, for which he was nominated for the Daytime Emmy Award for Outstanding Younger Actor in a Drama Series, as well as for his supporting role as Johnny Donnelly in the sitcom Two Guys and a Girl. Fillion received an honorary doctor of laws degree on May 30, 2025, from Concordia University of Edmonton.