Let's allow Robert De Niro to tell us about his experience making Awakenings with the much missed Mr Williams...

"I can think of lots of people who wouldn’t put me and Robin Williams together as close friends. Robin has this well-deserved reputation as an anarchic comic genius and, rightly or wrongly, I’m seen as this intense, “serious” actor. When we made Awakenings, though, Robin and I got on great. To be around someone with Robin’s energy fourteen hours a day, it’s impossible not to be tickled by him. I got the impression a lot of directors in the past had simply wanted Robin to show up and do his shtick. But Robin’s a really good actor, he’s very serious about his craft, and you could tell from our discussions that he really relished the opportunity to talk about acting. Oliver Sachs, the neurologist that inspired Robin’s character, had spoken to both of us at length and we were so impressed with his work that we both felt we owed it to him to do justice to his amazing story.

"So there you have us — two actors who get on well and are very committed to the movie they’re making. And then one of them goes and breaks the other one’s nose. And it’s not the guy who played Travis Bickle who breaks the nose, it’s Mork. What happened was, we were filming a scene that called upon Robin to be at his most animated. As you probably know, the guy never sits still anyway, so there was Robin pacing up and down and throwing his arms around, and there I am playing his catatonic patient. More than anything else during that scene, I was trying not to move. Because of the way I prepare for a role, I’d got the part down pretty good — so good in fact that, when Robin Williams’ elbow collided with my nose, I didn’t really flinch. It was only when the blood started to spurt out and the director Penny Marshall screamed “Cut!” that I realised how much damage had been done. Of course, Robin was mortified — “Oh, Robert, I’m so sorry! What have I done?”

"The thing is, I’d broken my nose before when I was young and when Robin whacked me, he straightened it back out again. I like to think it says a lot about Robin Williams that, when the guy breaks your nose, he leaves you looking better than you did before. Thanks, Robin, a professional couldn’t have done a better job."

Robin Williams opened up about some of his favorite roles in a 2013 Parade interview.

Mork & Mindy (1978-82)
“The first year with Pam Dawber and the last year with Jonathan Winters were a joy. The two desperate years [in between] I don’t really remember because of craziness and drinking and the network; everything was kind of rough. But Pam always made the experience wonderful. She’s so giving and so kind. As crazy as I was, she brought me back to earth whenever we worked.”

The World According to Garp (1982)
“The first day of shooting, I started improvising, and [director] George Roy Hill said, ‘Oooh. Cut. Just say the lines. You’re trained as an actor. Commit to that.’ So after four years of doing Mork & Mindy, where you’ve got to riff and find something funny, I went, ‘Commit to this character, Garp, and you’ll find yourself.’”

Good Morning, Vietnam (1987)
“An amazing experience. A lot of Vietnam vets like it because it’s not a combat movie. It reminds them of Vietnam in their non-combat moments, like in Saigon. It’s also a story of unrequited love. He doesn’t get the girl. A bit like we didn’t win [the war]. It was a draw.”

Mrs. Doubtfire (1993)
“A bit like demonic possession. Once in the right makeup and finding that voice, I was so freed up. You know, that very sweet voice. Initially she sounded like Margaret Thatcher. Scared the hell out of children. I went, no, no. Make her very soft, and very dear, and say horrible things in that soft voice. The idea of that film, which literally came from a divorce counselor in my first marriage, was, ‘Don’t use your children as little hostages. Just treat them with love and respect and you can get through this.’ ”

The Birdcage (1996)
“My favorite scene is the history of dance. And working with Nathan Lane was a blast—just to build off of our characters, the love for each other, which was wonderful. It got interesting reactions. Some people said, ‘How could you do that?’ Yet the idea of them loving their family, making this sacrifice for their kids, that’s why I loved it. In the end, you realized how damaged [bigots] are.”

Good Will Hunting (1997)
“One of the best experiences ever making a movie. It’s so well-written. I knew Matt Damon and Ben Affleck were really talented. As actors, they were both studly young men, and they had great writers’ chops. I didn’t have any idea what they’d do [in the future]. Ben, at the time, wanted to be a star. Matt was going, ‘I want to be an artisan,’ a guy who just pursues his craft. Which he’s done, brilliantly. Matt sampled [celebrity] and eventually went, ‘I’m going to be quieter, have a not-so-public marriage.’ He just lives his life. Ben kind of went off, then came back brilliantly.”

One Hour Photo (2002)
“Probably my favorite creepy movie I’ve ever done. It disconcerted people in a very good way. It’s about the idea of someone living vicariously through someone else’s life, before all of the stuff with social media on the Internet. It is very, very minimalist, but I’m really proud of it.”

World’s Greatest Dad (2009)
“It’s really good, and very dark. I loved doing that movie, working with a great friend and a great director, Bobcat Goldthwait. He makes these weird little movies and he’s so film-savvy that he knows how to make them for nothing.”