Bartholomew "Bart" Simpson is voiced by Nancy Cartwright (that's right, a woman!) and is Homer and Marge's only son on The Simpsons.  Bart is an underachiever and was definitely much more of a bad boy in th ebeginning seasons of the show.

Now, Bart, although he has not aged, has certainly matured as a character.  Do the Bartman people.

Bart Simpson Quotes

(The family watches Homer's launch on TV.)
Bart: Go, Dad, go!
Lisa: How doth the hero, strong and brave, a celestial path to the heavens paved!
(The family stares at her.)
Lisa: Go, Dad, go.

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

Bart

The Simpsons Quotes

(The family watches Homer's launch on TV.)
Bart: Go, Dad, go!
Lisa: How doth the hero, strong and brave, a celestial path to the heavens paved!
(The family stares at her.)
Lisa: Go, Dad, go.

Mr. Burns: I specifically said, no geeks!
Milhouse: But my mom says I'm cool...