does this show have voice actors for their characters?
Yes. I has six main cast members
The Simpsons
"The Simpsons" has six main cast members: Dan Castellaneta, Julie Kavner, Nancy Cartwright, Yeardley Smith, Hank Azaria, and Harry Shearer. 
what is treehouse of horror? Third episode of "The Simpsons"' second season how many seasons are there in total? 31 so far what is the theme of this episode? Three scary stories told by the Simpson children in the family's treehouse who are the characters in this episode? Homer, Bart, Lisa and Maggie when did this tv show start? December 17, 1989 who is the producer of this show? James L. Brooks
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The Simpsons [SEP] Voice actors
"The Simpsons" has six main cast members: Dan Castellaneta, Julie Kavner, Nancy Cartwright, Yeardley Smith, Hank Azaria, and Harry Shearer. Castellaneta voices Homer Simpson, Grampa Simpson, Krusty the Clown, Groundskeeper Willie, Mayor Quimby, Barney Gumble, and other adult, male characters. Julie Kavner voices Marge Simpson and Patty and Selma, as well as several minor characters. Castellaneta and Kavner had been a part of "The Tracey Ullman Show" cast and were given the parts so that new actors would not be needed. Cartwright voices Bart Simpson, Nelson Muntz, Ralph Wiggum and other children. Smith, the voice of Lisa Simpson, is the only cast member who regularly voices only one character, although she occasionally plays other episodic characters.