Has Yeardley Smith ever voiced any character besides Lisa?
According to IMDB no.
Huh. I’m just two days older than Lisa Simpson. Cool.
While she hasn’t done voices for any of the regular characters, or even secondary or tertiary characters other than Lisa, she has done a few one-shot characters. The one that comes most to mind is when Lisa sees a movie about the Tango De Le Muerte, or something, and the voice of the girl that dances is Yeardley Smith speaking in a bad Spanish accent.
There’s another one where Homer meets an island version of Lisa when he’s a missionary, whom he dubs Lisa Junior.
Lisabella. That’s her name with a “bella!”
It’s been so long since I saw the episode with Lester and Eliza that I’m perfectly prepared to be wrong, but I’m pretty sure Yeardley did the voice of Eliza.
Edit: Provided, of course, that Eliza even had any lines in that episode.
She didn’t.
Smith sounds almost exactly like Lisa - just older. So she’s not going to be in demand for other voice work like a Tress MacNeille is.
That was going to be my question: Does she just not have the range of the other voice-actors, or does she just not want to do any other character?
I’ve heard her say that any other character she’s tried just sounds like Lisa doing a character. I’ve definitely heard her do some one-offs, especially in earlier episodes, but you always know it’s her (which can’t be a plus for a voice actor).