Disco Stu is, above all, a man of principle. He does not advertise. And once he makes a commitment, he sticks with it. Disco Stu made Disco his life, and twenty five years after its demise, he's not giving up on it, even if he's grown to hate it. That's the kind of man Disco Stu is, and it deserves recognition.
Disco Stu first appeared in the season seven episode "Two Bad Neighbors," (the one where George Bush the Elder moves in across the stree) attending the Evergreen Terrace garage sale. It was when Homer's "Disco Stu" jacket was pointed out to him that we learned of Disco Stu's principled stance on advertising himself. (Homer had originally tried rhinestoning Disco Stud onto his jacket, but ran out of room.)
Stu was voiced in that initial episode by Phil Hartman, something I never knew until recently. He likely may have disappeared after that episode (thus making him eligible for my forthcoming "Best One Shot Simpsons Characters" list) but for whatever reason, the creators brought him back, with Hank Azaria taking over the role. Disco Stu has appeared in numerous episodes since and had a few lines here and there, hitting on Marge and promoting the Disco lifestyle. He has yet to be featured significantly in an episode, which is odd in this day age when every bit player seems to have had his or her day in the sun (Jeez, even Gil's had an episode dedicated to him...).
Whether or not Stu ever gets the thrust into the spotlight or not, one thing will always remain true: this stalwart champion of Disco deserves our respect and admiration.
Favorite Disco Stu line: Hey, Disco Stu doesn't advertise!
*It has been suggested by some (cough Dr. Bitz cough) that I need to nut up, take a stand and actually rank my favorite characters from ten to one. Never one to back down from a challenge that isn't too hard, after I have posted all ten of my favorite characters' individual entries, I will then post a list counting down from ten to one.