LOS ANGELES -- Jim Parsons cherished the opportunity to work with Stephen Hawking, but admitted he was a bit intimidated to meet the celebrated theoretical physicist.

Hawking or his voice appeared in seven episodes of Parsons' hit series "The Big Bang Theory."

"So much of our show is related, based on, adjacent to everything that Stephen Hawking did, strove to do, thought about, was passionate about through his entire life and career. The fact that he knew of our show, was interested in being on it, was willing to come play with us group of monkeys for a couple days was really moving," said Parson.

"It was just, it was an amazing experience. It was an intimidating one. I'd be lying if I said I was comfortable. ... To get to finally meet him was, it was just overwhelming," he continued. "And it's one of the things that's kind of bittersweet in a way because once he's passed now and now we're talking about him, it really hammers home how fortunate I was to get to be with him.

"At the time, it was just like this is neat and I know it's neat intellectually, but emotionally all I can think of is 'I want to get out of here before I embarrass myself,"' Parsons said.

Hawking, who died March 14 at age 76, became the public face of science genius. He also appeared on "Star Trek: The Next Generation" and voiced himself in "The Simpsons."

"His willingness to be part of our world, to come and be part of our show, was an extraordinary acknowledgement ... it felt like maybe we were doing something worthwhile that he would agree to participate, you know? He first was on the show six years ago and it was hard to believe this is really happening, you know? We were really lucky. We got to work and spend time with Stephen Hawking. I mean how blessed is that? How fortunate can you get?" said "Big Bang" executive producer Chuck Lorre.

The "Big Bang" cast came together Wednesday for PaleyFest, the annual television festival in Los Angeles.