Actor David McCallum, who played the eccentric medical examiner in NCIS 40 years later, has died aged 90.

McCallum died on Monday of natural causes surrounded by family at New York Presbyterian Hospital, US broadcasting network CBS said in a statement.

“David was a gifted actor and author, and beloved by many around the world,” the statement said.

“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.”

Among the first to pay tribute was former NCIS colleague Michael Weatherly.

“David McCallum made every moment count, in life and on set. Let’s raise a jug and celebrate a funny fantastic authentic man. I’ve only got 3 autographs. Connery, Tony Bennett and McCallum. I felt the same way as Steve McQueen in this picture from The Great Escape: Wow! It’s David McCallum! No one did it better,” he tweeted.

“We were lucky to have him bring us Ducky. Let’s send all the love in the world to his beautiful family. Rest In Peace David.”

Another co-star, Lauren Holly – who played Jenny Shepherd on NCIS from 2005 to 2015 – weighed in with: “RIP David McCallum. You were the kindest man. Thank you for being you.”

NCIS executive producers Steven D. Binder and David North offered their own tribute.

“For over 20 years, David McCallum endeared himself to audiences around the world playing the wise, quirky, and sometimes enigmatic, Dr. Donald ‘Ducky’ Mallard,” they said in a statement provided to Deadline.

“But as much as his fans may have loved him, those who worked side-by-side with David loved him that much more. He was a scholar and a gentleman, always gracious, a consummate professional, and never one to pass up a joke.

“From Day 1, it was an honour 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.”

Tweet from @M_Weatherly

Scottish-born McCallum had been doing well appearing in films such as A Night to Remember (about the Titanic), The Great Escape and The Greatest Story Ever Told (as Judas). But it was TV hit The Man From U.N.C.L.E. that made the blond actor with the Beatlesque haircut a household name in the mid-’60s.

The success of the James Bond books and films set off a chain reaction, with secret agents proliferating on both large and small screens.

Indeed, Bond creator Ian Fleming contributed some ideas as The Man From U.N.C.L.E. was being developed, according to Jon Heitland’s The Man From U.N.C.L.E. Book.

The show, which debuted in 1964, starred Robert Vaughn as Napoleon Solo, an agent in a secretive, high-tech squad of crime fighters whose initials stood for United Network Command for Law and Enforcement.

Despite the Cold War, the agency had an international staff, with McCallum as Illya Kuryakin, Solo’s Russian sidekick.

The role was relatively small at first, McCallum recalled, adding in a 1998 interview that “I’d never heard of the word ‘sidekick’ before”.

The show drew mixed reviews but eventually caught on, particularly with teenage girls attracted by McCallum’s good looks and enigmatic, intellectual character.

By 1965, Illya was a full partner to Vaughn’s character and both stars were mobbed during personal appearances.

The series lasted to 1968. Vaughn and McCallum reunited in 1983 for a nostalgic TV movie, The Return of the Man From U.N.C.L.E., in which the agents were lured out of retirement to save the world once more.

McCallum returned to television in 2003 in another series with an agency known by its initials – CBS’s NCIS.

He played Dr Donald “Ducky” Mallard, a bookish pathologist for the Naval Criminal Investigation Service, an agency handling crimes involving the Navy or the Marines.

Mark Harmon played the NCIS boss.

McCallum said he thought Ducky, who sported glasses and a bow tie and had an eye for pretty women, “looked a little silly, but it was great fun to do”.

He took the role seriously, too, spending time in the Los Angeles coroner’s office to gain insight into how autopsies are conducted.

The series built an audience gradually, eventually reaching the roster of top 10 shows.

McCallum, who lived in New York, stayed in a one-bedroom apartment in Santa Monica when NCIS was in production.

McCallum’s work with U.N.C.L.E. brought him two Emmy nominations, and he received a third as an educator struggling with alcoholism in a 1969 Hallmark Hall of Fame drama called Teacher, Teacher.

He is survived by his wife of 56 years, Katherine McCallum, sons Paul, Valentine and Peter, and daughter Sophie.

– with AAP