Though it’s been three years since Robin Williams‘ tragic death, his close friends and former co-stars still fondly remember the late actor as one of the most special people they’ve ever met. “I don’t think any other performer made me laugh as much. He was a unique, tender-hearted spirit,” Pierce Brosnan, who worked with Robin on 1993’s Mrs. Doubtfire, told Closer Weekly in an exclusive new interview.

“He was happiest when he was performing,” director Howard Storm told Closer. Robin began his showbiz career in the mid-1970s by working as a stand-up comedian. In 1978, he landed a guest role on Happy Days as alien Mork from Ork. His appearance on the hit sitcom was so popular, Robin soon earned his own spin-off show, Mork & Mindy. “He was dazzling. People would come down from the [studio] offices just to stand on the set and watch him,” Happy Days star Marion Ross told us of Robin’s stint on the show.

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Robin and Pierce in 2005. (Photo Credit: Getty Images)

“His was a one-of-a-kind genius. I was there watching him create that part on his feet. I mean, I saw the light of God! There was a light on him,” Robin’s former co-star Anson Williams told Closer. “He was the kindest, nicest human being. The week after we shot his episode, he came back on a Friday night and gave everyone little gifts and thank yous.” His Mork & Mindy co-star Pam Dawber similarly loved Robin’s exuberant spirit. “It was always playtime for him,” she told Closer.

Though Robin enjoyed his instant success, it wasn’t an entirely easy time for the star. “It was surreal. In three weeks, you go from being a nobody to people knowing you everywhere you go,” the actor once said. Storm recalled Robin suddenly being as famous as his comedic idols. “Celebrities he was in awe of — [John] Belushi, [Robert] De Niro — flocked to him. That was a happy, exciting time for him,” he told us.

Near the end of his life, Robin sadly began suffering from what he thought was Parkinson’s disease. “It was affecting his memory and that must’ve been terrifying. He was all about his mind, all about control,” the star’s close friend Kevin Conroy told Closer. After nearly 40 years in Hollywood, Robin sadly took his own life at age 63 in August 2014. “He was the sweetest guy who always wanted to make sure everybody else was happy. He chose to go out rather than drag everybody down with him,” comedian Johnny Steel told us.

“It’s a feeling that really something enormous left the planet. What Robin shared was a magical way of looking at life, a way of seeing with humor that which would otherwise remain in the dark,” Leigh McCloskey — one of Robin’s Juilliard classmates — told Closer. “The world is better because he was here,” co-star Anson added.

For more on Robin’s life and legacy, pick up the new issue of Closer Weekly, on newsstands now — and sign up for our newsletter!