What happened to earn Harmon the leading role on NCIS and how it shaped the show are inextricably linked to The West Wing. Here's how. As Secret Service Agent Simon Donovan, Mark Harmon appeared ...

Before Mark Harmon starred in 'NCIS,' he guest-starred in 'The West Wing.' Here's who told him his character in 'The West Wing' would die. Before Mark Harmon starred in 'NCIS,' he went on 'The ...