After nearly two decades as the face of NCIS, Mark Harmon’s departure from the main cast left fans stunned and full of questions. As Special Agent Leroy Jethro Gibbs, Harmon brought a calm authority and emotional depth to the show that helped make it a global hit. But when Gary Cole stepped in as Alden Parker, the shift was unmistakable—and for many, unexpected.

While there was no dramatic firing or behind-the-scenes scandal, the truth is that Harmon had been looking to step back for some time. Reports suggest he wanted a lighter schedule and more personal time after years of leading a demanding network series. In fact, he played a key role in choosing how and when his character would exit, ensuring the transition was smooth both on-screen and off.

Enter Gary Cole, a veteran actor known for his versatility and presence. CBS brought him in not as a direct replacement for Gibbs, but as a way to steer the show in a fresh direction while still honoring its roots. Cole’s character was written with a different energy—quirky, sharp, and independent—to contrast with Gibbs’s stoic leadership style.

The shock for many fans wasn’t just the casting change—it was how seamlessly Cole fit in. While no one could truly replace Harmon’s legacy, Cole’s performance helped NCIS evolve and stay relevant in a new era. In the end, the change was less about replacing a legend and more about preserving the longevity of a beloved franchise.