The Sprint
Currently NCIS ranks as the “second longest running scripted, non-animated U.S.” prime-time series that is ~still~ on air. Law & Order: Special Victims Unit is number one. In fact, SVU has been running since 1999 and doesn’t look like it’ll be slowing down any time soon.
I Recall
When Caitlin Todd was poised to leave the show as per the wishes of Sasha Alexander, not everyone knew on set knew. In fact, Michael Weatherly said that he had no idea until February 2005. Actually it only became clear that Caitlin would be assassinated once he “saw the special-effects guy attaching a blood pack to [Sasha’s] hair.”