Star of one of the longest running dramas ever, NCIS, Mark Harmon visits his co-CBS bud Stephen Colbert on The Late Show!

That’s right, probably the most popular drama in the world right now is NCIS, which is almost midway through its 17th (!!!) season. There must be so many moments on set that star Mark Harmon cherishes. But for Harmon, that’s not necessarily the case.

Aww, isn’t that sweet? His favourite moment is the time he spends off screen with his NCIS cast mates – some of whom he’s worked with for 17 seasons! Wow!

Mark Harmon has had a long a fruitful career (believe or not, the man is 68 years old!). And he’s got the stories to back it up. Like that time he found himself literally between two legends of comedy, Johnny Carson and George Carlin.

There are not a lot of people left to brag about their experiences on The Tonight Show with Johnny Carson, or their having met George Carlin. And not only meeting both, but at the same time? That’s a unique experience for Harmon to cherish.

But The Tonight Show wasn’t his first shot at being a guest on a late night talk show. And thanks to Michael Cain, it wasn’t his last, either.

The Merv Griffin Show is merely a footnote in today’s television landscape, likely more notably a fun reference for Seinfeld fans than anything else. But Harmon had to get out there during his early days, and Merv Griffon was a huge name in the 1960s and 70s.

And, like previously mentioned, every actor has to get a start somewhere. And the lucky ones, and the ones with noteworthy talent, are taken under the wing of a more veteran actor. Mark Harmon was lucky (and talented) enough to find a mentor early on, to help him hone his craft and get used to the ins-and-outs of the industry.

Mark Harmon is still trucking along with NCIS, in its 17th season and having launched two spinoffs, NCIS: Los Angeles and NCIS: New Orleans. Watch new episodes of NCIS Wednesdays at 8.00 et/pt on Global!

Catch more of The Late Show with Stephen Colbert airing weeknights at 11.35 et/pt on Global, and watch the latest episodes online here on GlobalTV.com!