Kevin Sussman has warned fans that Stuart Fails To Save The Universe is "not comparable" to The Big Bang Theory.

The 55-year-old actor reprises his role as Stuart Bloom in the new HBO Max show, having first played the character from season two until its 12th and final run in 2019, but he has insisted the sci-fi won't feel too familiar.

He told TVLine: "It's not comparable to the original show. There's no need to deal with comparisons to the original because it's so different.

"It still has that Chuck Lorre DNA with the comedy, but it is definitely a different genre altogether."

The new single-camera sitcom comes from The Big Bang Theory creator Chuck Lorre, who called Kevin to pitch the project.

The actor recalled: "Chuck called me into his office and said, 'Do you know why you're here?' And I had no idea.

"He said, 'I want to do a spin-off called Stuart Fails to Save the Universe, which is a multiverse-type show, and we would have some of the original characters appear, but they wouldn't be who they were in the original show'.

"And he asked me if I would be interested in something like that. And I was like, 'Well, let me check my calendar....' "

Meanwhile, Kevin admitted landing a leading role in a Big Bang Theory spinoff wasn't something that had even entered his mind.

He told Deadline: "I just want health insurance. I've always just wanted to work, so this was not on my bingo card. I was not expecting this."

The sitcom also sees Bert Kibbler (Brian Posehn), John Ross Bowie (Barry Kripke) and Lauren Lapkus (Denise) return for a post apocalyptic comedy.

The logline for the show reads: "Comic book store owner Stuart Bloom is tasked with restoring reality after he breaks a device built by Sheldon and Leonard, accidentally bringing about a multiverse Armageddon.

"Stuart is aided in this quest by his girlfriend Denise, geologist friend Bert, and quantum physicist/all-around pain in the a** Barry Kripke.

"Along the way, they meet alternate-universe versions of characters we've come to know and love from The Big Bang Theory. As the title implies, things don't go well."