Homer Simpson, voiced by Dan Castellaneta, is the patriarch of The Simpsons and is definitely the main character.  Homer is an overweight, slob and a terrible father, but genuinely tries hard.

Homer previously had a job as safety inspector at Mr. Burns' Nuclear Power Plant, but good luck finding out what he's been doing for a living the last few years.

Homer Simpson Quotes

Homer: (Wearing glasses) The sum of the square roots of any two sides of an isosceles triangle is equal to the square root of the remaining side!
Man: (From inside a bathroom stall.) That's a right triangle, you idiot!
Homer: D'oh!

D'oh! Why do things that happen to stupid people keep happening to me?

Homer

The Simpsons Quotes

(Bart shows the whole classroom the tape for his project called, "How Kittens Are Born: The Ugly Truth")
Bart: and here comes Snowball II. This is the one we kept.
All: EWW!!
Bart: We were gonna keep the gray one, but the mother ate her.
All: EWWWWW!!
Martin: Mrs. Krabappel, he's traumatizing the children!
Mrs. Krabappel: As usual, I agree with you, Martin. Bart, shut that off and take your seat immediately!
Bart: Oh, look! This is really cool. When I hit reverse, I can make 'em go back in.
(The whole classroom screams)

Homer: (Wearing glasses) The sum of the square roots of any two sides of an isosceles triangle is equal to the square root of the remaining side!
Man: (From inside a bathroom stall.) That's a right triangle, you idiot!
Homer: D'oh!