The American funnyman, who died from a heart attack last month (Mar16), had taken few film roles in recent years, with his most prominent part corrupt politician Senator Stern in his friend Jon Favreau's Marvel superhero movie Iron Man 2.

Jon convinced the star to take a voice role as a porcupine called Ikki in his new version of The Jungle Book, his first film appearance since reprising the role of Senator Stern in Captain America: The Winter Soldier in 2014.

The director says that Garry was such a perfectionist about his work on the movie, he insisted on returning to record new lines for his character in the weeks leading up to his death.

"We recorded together," the filmmaker tells USA Today newspaper. "And he even popped into other (voice) sequences and offered advice. So he would stick around, he did that role. He did a great job.

"I spoke to him later and he said, 'Do you mind if I come back in? I have some new ideas.'...We brought him in. I’m very happy we did. He completely plussed (sic) up the scene and he added more humor. Which is amazing. I didn’t know there was that potential. But he was that kind of perfectionist."

Before Garry's death, Jon managed to show him completed scenes from the movie and says he will always treasure his friend's positive reaction.

"I got to show him sequences of the film that were completed," he adds. "And I got to see his reaction. Which will always be a fond memory. He was very generous with his enthusiasm."

Despite The Larry Sanders show star's comic talents, Jon admits it was a struggle to get his pal to take the part, saying, "It would take a lot of doing to get him to do something. He tended to want to operate behind-the-scenes for the most part."

Garry acted as a mentor and sounding board to a number of comedians and filmmakers, with stars including Amy Schumer, Ricky Gervais, Judd Apatow, Conan O'Brien and Seth MACFarlane all offering heartfelt tributes in the wake of his death.

Moviegoers will be able to see the late funnyman's final voice role when The Jungle Book hits cinemas in the U.K. and U.S. on 15 April (16).