Given the star-studded, name-dropping natures of their plots and backdrops, we decided to exclude some of Entourage and 30 Rock's finest guest gigs here, and opt instead for the more unexpected drop-bys from elsewhere, some of which you probably won't have seen.
In no particular order, here are our 16 favourite tv cameos ever:
1) Michael Palin, Home and Away (1997)
An utterly out-of-context outing in Summer Bay for the Monty Python legend, who decides to slip on a modern-day Victorian muscle man swimming suit and pretend to be a very British surfer who’s scared of both sharks and jellyfish. This is bizarre, and yet so glorious:
2) Gary Lightbody from Snow Patrol, Game of Thrones (2013)
In fairness, Game of Thrones is no stranger to the odd gas cameo. Coldplay drummer Will Champion and Reykjavik post-rockers Sigur Ros have stolen a couple of scenes in the blockbuster series' acclaimed 5 seasons to date, and rumours are rife that next season will feature an unlikely appearance from the cast of It's Always Sunny in Philadelphia.
Back in Season 3, however, it was Snow Patrol lead singer Gary Lightbody who stole the show with a ballad on horseback:
3) Britney Spears, Sabrina The Teenage Witch (1999)
The pop icon and teenage witch were besties at the turn of the millenium, and actually reunited earlier this year. In season 4, episode 1 of Sabrina, Spears dropped in to sing 'Crazy,' the official video for which starred Sabrina herself - Melissa Joan Hart - the same year.
4) Justin Bieber Gets Blown To Shit, CSI (2011)
The Canadian singer played Jason McCann, a member of an anti-government family whose foster father is in jail and whose brother is seeking revenge against the police. He gets promptly filled with bullets, which evokes a very awkward satisfaction amongst viewers who are sick of his shite.
5) Little Britain's 'Lou and Andy' on Neighbours (2007)
Matt Lucas and David Walliams drop into the background as their Little Britain characters for literally no reason at all, and it's just bloody fantastic.
6) Stephen Hawking, Big Bang Theory (2012)
The legendary theoretical physicist is a fan of The Big Bang Theory and requested to watch a rehearsal of the episode after filming his scene. Simon Helberg (Howard) does an impression of Hawking's voice in the episode and felt slightly uncomfortable mimicking the world's greatest scientist in his presence, but Hawking supposedly enjoyed it.
7) Kings of Leon, It's Always Sunny in Philadelphia (2011)
Not the best footage, sadly, but the episode is well worth a watch on Netflix. The world-famous Tennessee rockers turn up at the gang's school reunion on the cult comedy and produce one of the funniest cameos ever. At first you see Jared and Nathan and think, "Is that Kings of Leon?" Then Caleb strolls in, destroying the air of subtlety and amping up the humour. Great stuff.
"And the Emmy for Breakthrough Acting in a Comedy Series goes to........Jared Followill, Bartender #2!!!!!"
— Jared Followill (@youngfollowill) December 9, 2011
8) Ian McKellen, Coronation Street (2005)
Two years removed from the Lord of The Rings trilogy, the man who owned the big screens as Gandalf turned up in Weatherfield as a con-artist novelist, seemingly just for the craic. Incredible scenes down th'Rovers.
9) The Killers, The OC (2004)
It's not a 'funny' cameo, but kind of cool to look back on considering that the Vegas rockers only released their debut album 'Hot Fuss' a couple of months prior, and they appeared on the drama series to self-promote. 11 years later, The Killers have sold 22 million records worldwide.
10) George Clooney, Downton Abbey (2014)
filmed for ITV’s Text Santa charity initiative and not the actual show — we see Lord Grantham go through an It’s a Wonderful Life experience: what if he had never been born? I mean, let's be honest, this is insanely awkward. But for some reason, just so great.
11) Boy George, The A Team (1984)
Clooney's Downtown cameo is only the second greatest tv guest spot by a boy named George...
12) Larry David, Hannah Montana (2007)
Every fibre of David's being must have been burning on the set of the Disney Channel hit, but kids come first, eh? The Curb Your Enthusiasm star's two daughters were massive Hannah Montana fans, and begged Daddy to get them a gig on set. And, even in the presence of a pre-twerk, pre-gobshite phase Miley Cyrus, Larry kills it:
13) Heidi Montag, Spencer Pratt and Kim Kardashian, How I Met Your Mother (2009)
You'll remember this one. 'Reading a magazine.' This is great purely because of Marshall's description of Mrs. Kardashian-West.
14) David Beckham, Only Fools and Horses (2014)
Ah, this is just lovely jubbly. David Beckham might be the nicest, most down-to-Earth 'star' on the planet, but - even as a life-long Manchester United fan - I probably didn't realise he had such a comedic side until I saw him star in Only Fools and Horses' Red Nose Day special last year.
There was something poignant about seeing the cockney kid-turned-athlete-turned-superstar take it back to his roots on the London streets, alongside two of the city's greatest ever characters. Worth sticking this out 'til the end, trust me.
15) Prince, New Girl (2014)
The artist formerly known as The Artist Formerly Known As Prince dropped into New Girl last year, giving Zoey Deschanel's character, Jess, an internal an external makeover - which included a savage ping pong battle and some tongue-in-cheek relationship advice. But the funniest part of Prince's New Girl cameo has to be Schmidtty's delayed reaction:
16) The Cast Of Seinfeld, Curb Your Enthusiasm (2009)
11 years on from the legendary sitcom, Larry seeks to give the Seinfeld cast a proper reunion to some typically disastrous consequences. The final Curb episode of season 7 is brimful of meta-humour, and perhaps best remembered for Jerry's "We already screwed up one finale!" line - an allusion to the fact that the Seinfeld finale was met with largely mixed reviews.