2003 in American television

In American television during 2003, notable events included television series debuts, finales, cancellations, and new channel initiations.

NCIS (originally referred to as Navy NCIS), a spin-off of JAG, premiered on September 23, 2003 on CBS, becoming the third-longest-running scripted, nonanimated U.S. prime-time TV series currently airing, and has later spawned multiple spin-offs and was voted America's favorite television series in 2011. Other notable shows that premiered that year included Arrested Development, Jimmy Kimmel Live!, Two and a Half Men, The Venture Bros., One Tree Hill, The O.C., Nip/Tuck, and Teen Titans.

Later 2010s/2020s TV shows like Better Call Saul (2015-2022) and the television adaptation of The Last of Us (2023–present) are set in 2003.

Television debuts

 * Chris O'Dowd – Red Cap