Shane Brennan (born 1957, Bendigo, Victoria, Australia) is an Australian-born U.S.-based television writer and producer, best known as the executive producer of the American CBS drama NCIS, as well as the creator of the NCIS spin-off series, NCIS: Los Angeles.
Brennan's other television credits include Special Squad, The Flying Doctors, All Together Now, King & Maxwell, State Coroner, Stingers, Flipper, CSI: Miami, and Summerland. By 1981, he had abandoned journalism for television scriptwriting. He has early credits on Special Squad, Prime Time, In Between, Embassy, The Flying Doctors, Altogether Now and Ocean Girl.
From the mid-1990s he worked on American cable shows shot in Australia – of which Flipper is the only named example in IMDB. That gave him exposure, friends in the U.S. and an agent. As he said, "I started travelling backwards and forwards for about five years – usually four or five times a year, coming for two or three weeks at a time, doing lots and lots of meetings, all at my expense."
He is the current showrunner on NCIS: Los Angeles and remained an executive producer of NCIS (TV series) until the end of the eleventh season, despite having handed the day-to-day showrunner operations over to Gary Glasberg after the original show's 8th season.