The end of the popular comedy series The Big Bang Theory is approaching: The 12th season will be the last and many fans are already speculating on how the series could end. But TBBT fans probably wouldn't have expected such a star-studded episode.

'The Big Bang Theory' Cast

Lindsey Craft is "Zack's" new girlfriend

The Big Bang Theory has a new main cast member!

As "CBS" announced on Twitter recently, William Shatner (87) will be appearing in the upcoming last season. The sci-fi icon, who will assume a guest role, is known all over the world for his iconic portrayal of "Captain James T. Kirk" in the Star Trek TV series as well as many movies.

William Shatner turned down a guest role on The Big Bang Theory

In 2016, William Shatner already announced that he rejected an offer to star in The Big Bang Theory: he was supposed to play an overdrawn version of himself. Eventually, the producers of the popular show were able to get him aboard. "Sheldon" (Jim Parsons, 45) and the rest of the cast are huge fans of Mr. Shatner so they sure are looking forward to this one!

"Captain Kirk" will be joined by another Star Trek alum

As announced on Twitter, this special appearance will be an epic episode which will focus on the role-playing game ‘Dungeons & Dragons’. In addition to Shatner, Wil Wheaton, a former cast member of Star Trek: The Next Generation, will also appear in the episode. They will be joined by filmmaker Kevin Smith, Joe Manganiello and ex-basketball star Kareem Abdul-Jabbar! There’s no fixed air date for the episode yet, so stay tuned!