This is an article about the character. Are you looking for Dr. Demento, the guest star?
Barret Eugene "Barry" Hansen, better known as Dr. Demento, is an American radio broadcaster and record collector.
Lisa told Bart that his mortal enemy had been on the radio and he turned it on. Dr. Demento's voice was heard. When Bart heard it, he tossed the radio out the window. Lisa told him that she had meant his other mortal enemy, Sideshow Bob.
- Dr. Demento seems to be Bart's enemy, but the reason is unknown.