Ron Howard Remembers 'American Graffiti ' Costar Cindy Williams: 'A Big Sister Energy Around Me'

The entertainment world is reacting to the loss of Cindy Williams, who died Monday at the age of 75.

Ron Howard, who originally starred with her in the classic 1973 film American Graffiti, had memories to share of the actor who made waves in the same era — most notably in Laverne & Shirley, which was a spinoff of Howard's most famous sitcom Happy Days.

"I'm shocked because I hadn't seen her for years and years," Howard recalled to PEOPLE, upon hearing of her death. "We connected at an event in Palm Springs [California] last year, and I was just so taken by how her intelligence, energy, and sense of humor...was still in high gear. And so it's really a shock to imagine that spark is gone."

Howard described the professional bond the two shared, including memories of memorable movie scenes.

"In American Graffiti, she was 24 and I was 18, and I had my first kissing scenes with her, but they weren't very romantic because she knew that she had this nervous kid on her hands and she had to take charge of the situation," he said.

"And so she was like, 'Here's how we got to kiss for the camera. Here's what we have to do.' She's always had almost a big sister energy around me."

"We wound up over a period of about five years working together a lot, being cast in other comedies, in dramas," Howard continued. "The Laverne & Shirley spinoff from Happy Days, it was so interesting. We had terrific acting chemistry, but she always treated me like the kid."

Howard continued with glowing recollections, including noting that Williams was "highly intelligent, very funny, very astute about the world around her. Very skeptical of glamour or the illusions around our business. She fell prey to none of that."

"She loved her work and her art and gave it everything that she had, and she also always found her way to put her stamp on what she was doing. She really was dedicated creatively, and I took notice of that and tried to draw inspiration from it."

"I think she'd like to be remembered for the variety of roles that she played," he noted. "Even though she was the most famous for Shirley...she also thought of herself as a character actress. I think she'd want people to think of her in that way."

"I'm glad to be able to comment on her life because she lived it with a lot of integrity," Howard said. "I've always respected her."