Career
Brennan"s other television credits include Special Squad, The Flying Doctors, All Together Now, King & Maxwell, State Coroner, Stingers, Flipper, Computer Society of India: 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 United States. 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 (television 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. Despite stepping down after NCIS Season 8, Brennan continued to be credited as an Executive Producer up until the NCIS Season 11 finale episode, "Honor Thy Father" as his name was subsequently removed from the Executive Producers"s credits that appear after the final scene of an NCIS episode with "Honor Thy Father" marking Brennan"s final credited appearance.
