Billy Crystal still thinks about his late father "all the time".

The 76-year-old actor - who has been married to Janice Goldfinger for nearly 55 years and has Jennifer, 51, and 47-year-old Lindsay with her - was just a teenager when he lost his dad Jack to a heart attack in 1963 and is very touched when others who knew him remind him "talk so lovingly" about his dad.

Speaking on 'Sunday TODAY with Willie Geist', he said: "He had a great passion for people. Even to this day, those who are still around who knew him talk lovingly about him, that means everything to me.

"I think about [what he's missed] all the time. The babies being born, the grandchildren. It's those moments. The career moments of course."

The 'Monster's Inc.' star couldn't stop thinking about his father or his mother Helne - who died in 2001 at the age of 86 - when he received a Kennedy Center honour towards the end of last year but is sure that they are still watching over him.

He said: "I couldn't get him out of my head, and my mom too, at the Kennedy Centre. I kept saying 'Ah man, what they missed...' But in some ways, you think that they have seen. They have been watching.

"The thing that would be most important would be that he could say 'You did good. You're a good man...' That would mean the most."

During his lifetime, Jack Crystal had owned and operated the Commodore Music Store in New York City and in 2015 the NYU Tisch School of the Arts decided to rename their theatre after him.

At the time, Billy said: "My family and I are moved and honored that this theater is now named for my father. Jack Crystal was a rare man who devoted his life to the nurturing of great musicians and their music. The thought that young artists will grow and express themselves in this space is incredibly powerful to me."