The Real-Life Agent Who Inspired NCIS' Leon Vance

Many of the characters on "NCIS" came about thanks to the imaginations of the show's writers. But the origin of actor Rocky Carroll's character is a little different. As Carroll revealed in an interview with CBS News, Leon Carroll Jr., one of the show's technical advisors, inspired the creation of Leon Vance, with whom he shares a first name. Coincidently, despite sharing the same last name, there's no relation between Leon Carroll Jr. and Rocky Carroll (via Chicago Tribune).

Leon Carroll Jr. joined the real NCIS in 1980 after serving as a marine. He even put his retirement on pause and joined NCIS again after the events of September 11, 2001. Around 2003, a different type of NCIS beckoned Leon to join its ranks, this time for the small screen.

Carroll shines as one of the show's best shots at authenticity. He has provided the team with plenty of real-world knowledge, from standard procedure to specific work lingo actual NCIS agents might say. And according to Carroll, the writers have been largely receptive to his advice or corrections. "I'd say that 80 percent of my suggestions are taken," he told the Chicago Tribune.