Julia

Julia was Homer's manager after he became a famous opera singer.

History
She first saved Homer and Marge from an angry mob of fans before becoming Homer's manager. She tries to seduce him, but Homer refuses. Not accepting refusal, she tries to kill Homer, first with a Cobra placed in his cereal box, and later with a poisoned blowdart disguised as a conductors baton, during a showing of The Barber of Seville. However, both attempts were thwarted, first by Homer repeatedly whacking the cobra against the refrigerator door causing it to be dazed for the remainder of the morning, and the second when Marge stops her by hurling a French horn in the way, causing the dart to redirect back at her. However, the snipers actually saved her from poisoning by shooting her and then crashing the Chandelier on her, squeezing out the remaining poison. While she is being sent to an insane asylum, she swears vengeance on Marge, hinting that a Cable company is going to be involved in her revenge. Whether or not she will return to get her revenge on Marge (making her Marge's own "Sideshow Bob") remains to be seen.

Behind the Laughter
Julia appears in "The Homer of Seville" and, although she is white (or, in this case, yellow) in the show, she is voiced by Maya Rudolph, a black actress.