1. George Harrison - The Simpsons

Back when "celebrity tv cameos" usually meant special episodes where a celebrity would walk out and get huge studio-audience applause and then perform one of their songs or say their catchphrase, The Simpsons inverted the form by bringing in George Harrison then having him utter two sentences while Homer devours brownies in front of him.

Looking back on his time with his band The Be Sharps, Homer reminisces, Then came the greatest thrill of my life...

Harrison shows up for one more line at the end of the episode to rip on Homer's group re-uniting on a rooftop.

2 Hugh Jackman - X-Men: First Class

X-Men: First Class was a near-total-reboot of the X-Men franchise complete with a mostly all-new, younger cast, but the creators still reached out to Hugh Jackman about reprising his role of Wolverine, which he did, for exactly one ad-libbed sentence that earned the film its PG-13 rating:

3. Robert De Niro - Extras

Extras took the very concept of celebrity cameos to another level of craziness, but nothing was more elaborate than this cameo; after establishing for two seasons that Ricky Gervais' Andy Millman character got into acting because he idolized Robert De Niro, Stephen Merchant's hopeless agent character promises to set up a meeting with him, but Andy doesn't believe him and skips out.

So, the show literally booked Robert De Niro to just sit there and play with a novelty pen:

4. Bob Saget - Half Baked

Bob Saget appeared in Half Baked to deliver one line at a support group for drug addicts, a line which we would later come to regret when, he claimed, people on the street constantly shouted the line at him when he in public with his children:

 

 

5. Robert Patrick - Wayne's World

Robert Patrick, aka The T-1000 from Terminator 2, makes one of the most out-of-the-blue cameos imaginable when Wayne's World breaks the movie-universe-4th-wall for an extremely weird one-off joke:

6 Lauren Bacall - The Sopranos

In Sopranos Season 6, Christopher flies to Hollywood to approach Ben Kingsley about being in his movie, but after failing to win him over, Christopher panics and ends up mugging Hollywood legend Lauren Bacall so he doesn't go back east empty-handed. On a show of wonderfully surreal moments, the fact that actual Lauren Bacall agreed to this is just really amazing:

 

7. Jonathan Frakes - Futurama

Futurama reunited almost the entire cast of the original Star Trek for the episode "Where No Fan Has Gone Before," but also snagged Jonathan Frakes, aka Commander Riker from Next Generation, just to say one line:

 

8. Marcel Marceau - Silent Movie

Mel Brooks' Silent Movie is a parody/homage to slapstick movies of yesteryear featuring tons of big-time celebrity guest stars -- Paul Newman, James Caan, Liza Minnelli, and more -- but they also recruited Marcel Marceau, the world's most famous mime, and gave him the only actual spoken line in the film (him saying "NO" to doing the movie):

 

 

9. Richard Dreyfuss & Roy Scheider - Family Guy

Family Guy always goes the extra mile to bring in actual celebrities for a one or two-line throwaway joke (Charlie Sheen, for example), but one of the most unexpected was their brief reunion of the two leads from Jaws who appear as the voices in young-Peter and his friends' heads, and ended up being the last thing Roy Scheider ever appeared in (airing a couple months after he died in 2008):

 

 

 

10. Paul McCartney on The Beach Boys' song "Vegetables"

Possibly the most bizarre and unexpected A-List cameo in media history traces back to The Beach Boys' recording sessions for their Smile, when Paul McCartney stopped by the studio while they were recording a song called "Vegetables" and the band ended up recording the noises of McCartney chewing celery to use on the track:

 

 

 

Honorable Mentions: Two of the best recent cameos, Bill Murray in Zombieland and Johnny Depp in 21 Jump Street, were just a little too long to totally fit the theme. Also The Simpsonshas about a hundred more examples, from the Cast of Cheers to The Ramones, as doesFamily Guy. And Conan O'Brien's cameo in The Office is great but all the uploads of it online suck, and we had to cut something to get down to 10. Also Stan Lee, Stephen King and Alfred Hitchcock in every movie. And Roman Polanski putting himself in Chinatown.

Also, there's probably no better "Recruit a huge celebrity for something extremely small and stupid" example than George Clooney voicing the dog on South Park (though again, doesn't totally fit the criteria. Though I guess not all these clips were technically 30 seconds. Ah well, so something on the internet is imperfect. I apologize for screwing it up for everyone.)