There are few sitcoms as hilarious, heartwarming, and long-lasting as"The Big Bang Theory.

Here are the “Big Bang Theory” stars who have died.

Howard Wolowitz’s mother, Mrs. Wolowitz, was somewhat of an enigma.

Stan Lee smiling

Sadly, the actor behind Mrs. Wolowitz, Carol Ann Susi, had a tragic ending.

According toThe Hollywood Reporter, Susi died from cancer at the age of 62 in 2014.

Wolowitz died peacefully in her sleepwhile vacationing in Florida and the main characters grieved for her.

Carol Ann Susi

According toThe Hollywood Reporter, Hawking was a part of seven episodes of the sitcom.

Creator Chuck Lorre told the publication that Hawking was a true professional.

“All of professor Hawking’s dialogue was preprogrammed and triggered through a voice synthesizer,” Lorre said.

Stephen Hawking on “The Big Bang Theory”

He wanted to ‘act.'"

Sadly,Hawking diedin 2018 when he was 76, leaving a huge legacy behind.

So, whenLee appeared on the series, it was obviously a big deal.

Stan Lee on “The Big Bang Theory”

It’s obvious the characters were a bit obsessed with Lee, and who could blame them?

To say that Lee’s impact was unparalleled would be an understatement.

West appeared on the Season 9 episode"The Celebration Experimentation,“playing himself.

Adam West wearing sunglasses

Fisher appeared in aSeason 7 episodein which Sheldon hangs out with James Earl Jones.

At one point, the two appear on her doorstep toding-dong ditch her.

Sadly, Fisherdiedafter going into cardiac arrest when she was 60 on December 27, 2016.

Carrie Fisher on “The Big Bang Theory”

Specifically, Sheldon related to and loved Spock, played by actor Leonard Nimoy.

But that wasn’t always the case.

Leonard Nimoy speaking