For many celebrities, an appearance on The Simpsons is one of the highest accolades imaginable. A trip to Springfield is often viewed as a sign that you've made it as a pop culture icon and some famous folk are probably better remembered for their time on the show than for anything they've achieved in the real world.
That being said, sometimes celebrity guests aren't just happy to turn up, record their lines, and go home; some have their own terms and conditions before they allow themselves to get Simpson-ized. Some have legitimate reasons for making their demands and some... well, let's just use the word "diva" and leave it there.
Some of these demands had very little impact on the show itself, but some of them actually did impact the plot of the episode. One change was so big that that it made a permanent change to the show's continuity, which happens in The Simpsons about as often as Mr. Burns donates to the local orphanage.
Regardless of their effect on the show, the following ten examples are reminders than even Simpsons writers aren't immune to the sway of celebrity.
10. Dustin Hoffman & Albert Brooks - No Real Names
In the early days of the show, big celebrities didn't want their real names to be used in the credits. There are several examples of this (one of which we'll get to much later), but perhaps the most well-known is when "Sam Etic" voiced Mr. Bergstrom in Season 2.
Of course, "Sam Etic" isn't a real person; it was a clever play on words alluding to the Jewish heritage of both Bergstrom and the man who voiced him, Dustin Hoffman.
The double Oscar winner was hesitant to use his real name as The Simpsons did not have the same level of prestige in its early days as it does now and Hoffman worried that appearing on a cartoon would damage his credibility.
Another early guest star who went under a pseudonym was Albert Brooks, who voiced adulterous bowling instructor, Jacques, in Season 1. Well, we say "pseudonym" - the future Finding Nemo star was credited as "A. Brooks" on that episode which would be like Richard Bachmann publishing a book under the name "S. King". "A. Brooks" did eventually use his real name on The Simpsons, most notably when he played Hank Scorpio seven years later.