Troy McClure was voiced by Phil Hartman until the actor's untimely death in 1998 and the character has been retired since then.  McClure is a washed up star from the 1970s that is the star of many infomercials, educational films and movies.  At one point, McClure married Selma in order to attempt to revive his career after rumors of a paraphilia.

Troy McClure Quotes

Troy McClure: I'm actor Troy McClure. You may remember me
from such TV series as: Buck Henderson: Union Buster and Troy & Company's Summertime Smile Factory.

(Troy McClure hosts an infomercial for a new type of candy that cleans and straightens teeth.)
Troy McClure: Ladies and gentlemen, I'd like you to meet the inventor, Dr. Nick Riviera.
(Audience applauds)
Dr Nick: Thank you, Troy! Hi, everybody!
Audience: Hi, Dr. Nick!

The Simpsons 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!

(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)