The Princess: Hard to beat Glenn Close’s debonair meddler in Dangerous Liaisons.

Somehow, Kathryn manages it. She lives in an opulent New York penthouse and entertains herself by interfering with other peoples’ relationships: namely those of half-brother Sebastian.
 
How Spoilt? This girl has an outfit change every ten minutes, and spends any excess cash on cocaine.

Karmic Punishment: Her malevolent, drug-taking ways are exposed to the entire school during her stepbrother's funeral. Justice. Served.