Ken Bates
English soccer clubs shudder when they hear Bates’ name because he was one of the worst owners ever. His time in charge of Chelsea ended with a massive racism scandal. Later, he took over Leeds United and caused them to plummet down the leagues (via The Guardian).

There were positive aspects to his ownership of Chelsea because he modernized the club and improved its facilities. But his later behavior was inexcusable. Furthermore, some Leeds fans like Bates because he stabilized them in the Championship but he had no moral compass.