9. Ralph Wiggum
Ralph’s voice has actually changed a couple of times on the show, with the first being incredibly noticeable and jarring, and the second much slower and easier to miss. Considering he’s one of the most popular side characters though, neither change has gone unnoticed.
In Ralph’s first appearance, he actually has Nelson’s voice. It makes some sense, given both are voiced by Nancy Cartwright, but considering how at odds their personalities are it’s very unsettling on a rewatch.
Of course, that’s if it even is Ralph. Sure, he looks just like Ralph, dresses the same way and like the real Ralph, is in Lisa’s class, but fans with way too much time on their hands have been known to argue over whether this is the true Ralph or just some deep voiced doppelgänger. His name is never stated, to be fair.
However, it very clearly is Ralph and the voice was just because his character model was used before he was given a personality. Mystery solved.
The second Ralph changed is simply one that’s happened over time. As Ralph’s voice is so high and nasally, Cartwright has struggled to consistently reach it, and so it’s now a little deeper, but with more squeak.