Lisa Marie Simpson, voiced by Yeardley Smith, is Homer and Marge's oldest duaghter and the middle child on The Simpsons.  Lisa is very intelligent, plays the saxophone, is a vegetarian, Buddhist, and definitely a bit of a young political activist.  She's basically the complete opposite of her brother, Bart.

Lisa Simpson Quotes

Lisa: I'll study so hard I'll make the old me look like Bart.
Homer: That'd be one weird looking kid.

Anya: (in a girls voice) "Dear Lisa, as write this, I am very sad. Our president has been overthrown...(man's voice) and replaced by the benevolent General Krull! All hail Krull, and his glorious new regime! Sincerely, little girl."
Lisa: (groans)

The Simpsons Quotes

Marge: Tomorrow night, it might be nice to go out for dinner.
Homer: Tomorrow night? Friday? Pork chop night? Marge! We haven't missed pork chop night since the great pig scare in '87!

Wow, now I see why they call you Miss Hoover. You must have been vacuuming for an hour.

Bart