The Big Bang Theory has welcomed a long list of famous faces on to the show over its 12 years on air.
While some, including Billy Bob Thornton, Octavia Spencer and Regina King, played fictional characters, many appeared as themselves.
Below is a selection of some of the celebrities who guest starred.
Professor Stephen Hawking
The esteemed physicist made seven appearances on The Big Bang Theory, most notably in season five episode 21, The Hawking Excitation.
Hawking visits the university where the main characters work, causing Sheldon – who later faints in front of his idol – to demand Howard set up a meeting between the pair.
The second man on the Moon appeared in season six episode five, The Holographic Excitation.
Aldrin proved he was up for a laugh by gently mocking himself, being shown on screen reminding a group of children he had been to space.
Fisher, best known as Princess Leia in the Star Wars franchise, appeared in season seven episode The Convention Conundrum.
Her Star Wars co-star James Earl Jones brings Sheldon to her house before they ring the bell and run away, leaving Fisher on the doorstep holding a baseball bat.
Sheldon plays a crucial role in another celebrity appearance on The Big Bang Theory, this time one involving Marvel supremo and comic book pioneer Stan Lee.
Lee, who appeared in season three episode The Excelsior Acquisition, wore a Fantastic Four robe when opening the door to Sheldon and Penny, before becoming annoyed and calling the police.
West is best known for his portrayal of Batman in the 1960s series. He made a guest appearance on The Big Bang Theory’s 200th episode in 2016.
West was seen arguing with Leonard, Howard and Rajesh over who was the best Batman.
Shatner’s place in the sci-fi hall of fame is certain thanks to his portrayal of captain James T Kirk in the Star Trek franchise.
He made a cameo in Big Bang Theory’s 12th season, meeting a starstruck Sheldon who later throws up after meeting his hero.
Wheaton, who as a child star played Wesley Crusher on the television series Star Trek: The Next Generation, made frequent appearances on The Big Bang Theory.
Often portrayed as an enemy of Sheldon, Wheaton shared an emotional post on Instagram as the show was ending, praising The Big Bang Theory for including him while “mainstream Hollywood doesn’t seem to be especially interested in me and what I bring to a production these days”.
One of the richest men in the world and co-founder of Microsoft, Gates appeared on episode 18 of season 11, The Gates Excitation.
The billionaire bumps into Leonard, Howard and Rajesh in a hotel lobby.