NCIS: Origins has revealed the tragic backstory behind Gibbs’ best trait and the origin adds dark layers to something audiences have taken for granted. For almost 20 years, Mark Harmon’s Gibbs was the Special Agent In Charge on NCIS and even when several characters left and joined, Gibbs remained a steady and loyal leader. Gibbs is particularly known for being reserved and calm under pressure, but his best trait is his strong instincts. His incredible instincts have saved the lives of his teammates several times over the years and have helped cement him as one of the best NCIS characters.