The actor played Dr. Donald “Ducky” Mallard on NCIS.

McCallum appeared in 457 episodes of the series, which has run for 20 seasons to date.

Dresampled to create the iconic opening of “The Next Episode.”

LOS ANGELES - NOVEMBER 2: David McCallum of the CBS series NCIS, scheduled to air on the CBS Television Network. (Photo by John Paul Filo/CBS via Getty Images)

David McCallum.John Paul Filo/CBS

The actor also published a novel in 2016, titledOnce a Crooked Man.

From day one, it was an honor to work with him and he never let us down.

He was, quite simply, a legend.

He was also family and will be deeply missed."

“He always put family before self.