The Scottish actor died this week at the age of 90, according to reports.

McCallum is best known for his role in the espionage series The Man from U.N.C.L.E., but he also participated in several seasons of the acclaimed drama NCIS.

He portrayed Donald ‘Ducky’ Mallard, the show’s medical examiner, in the series.

And, in the aftermath of the actor’s passing, NCIS co-star Harmon, who memorably portrayed special agent Leroy Jethro Gibbs, delivered his own personal tribute to him.

Harmon stated in a statement to TVLine that working with McCallum was an honor.

“I was in awe when I first met him, and all of us on the show were honored to have toed a mark opposite him,” added the actor.

“My condolences go out to [David’s wife] Katherine and his family.”

His remarks came after the NCIS team issued their own statement on social media.

The statement said, “We are fortunate that CBS was David McCallum’s home for so many years and deeply saddened by his passing.”

“David was a gifted actor and author who was well-liked by people all over the world.” He had a great life, and his legacy will go on forever via his family and the many hours of cinema and television that will never be forgotten.”

“We will miss his warmth and endearing sense of humor, which lit up any room or soundstage he stepped onto, as well as the brilliant stories he often shared from a life well-lived,” the statement continued.

“Our hearts go out to his wife Katherine, his entire family, and all those who knew and loved David.”

McCallum, who was born in Glasgow but had spent many years in the United States before becoming a citizen in 1999, died on September 25.

At the time, it was confirmed that the actor had died of natural causes at New York Presbyterian Hospital.

David was a talented actor and author, and many people all over the world adored him, according to a CBS spokeswoman in a statement.

“He led an incredible life, and his legacy will forever live on through his family and the countless hours on film and television that will never go away.”

The children of McCallum’s first marriage—Val and Paul—as well as his wife Katherine, son Peter, and daughter Sophie—are all still alive.

Jason, his third son with his first wife, Jill Ireland, died in 1989.