17 Longest Running TV Shows of All Time, From "Grey's Anatomy" to "SVU"

• Seasons: 20
• Episodes: 450+ (Ongoing)

Similar to "Law & Order," "NCIS" combines the perfect amount of drama with crime to make for an entertaining series. Across over 450 episodes, the show centers around special agents from the Naval Criminal Investigative Service as they deal with day-to-day crime cases. Due to its popularity, "NCIS" has spawned several spinoff series, including "NCIS: Los Angeles," "NCIS: New Orleans," and "NCIS: Hawaii."