Maybe it's hard to believe, but famous TV series NCIS is a spin-off of the TV show JAG, by the producer Donald Bellisario.

The characters and concept of NCIS were first introduced in the eighth season's episodes of JAG. First seasons of the series weren't very successful, but by the sixth season it became one of the most popular TV shows in America. Having become a top 5 hit, it was later entitled America's favorite TV show.

NCIS tells a story of a team of special agents of the Naval Criminal Investigative Service and their investigations.

More Info: en.wikipedia.org