Jeff Loria(Florida Marlins/Montreal Expos) - Tanked the Expos, threatened his way to a 650 million dollar arena, promptly gutted the team before he had to pay anyone.
Pocklington(Oilers) - Sold the greatest hockey player ever to keep his house of cards empire alive, blackmailed the city many times, sold the Oilers to Houston, and is now nothing more than a common con-artist who was recently on trial for fraud.
Charles Wang(Islanders) - One of the worst run franchises in pro-sports
Mike Brown(Cincinnati Bengals) - terrible team, rarely makes the playoffs, Owner insists he runs the franchise himself and refuses to hire a GM
Art Modell(Baltimore Raven) - up and decided he didn't like Cleveland anymore, broke contract and moved the team to Baltimore.
Marge Schott(Cinncinati Reds) - Big time racist, hated her own players, once refused to pay for ambulance transportation for one of her players injured on the field.
Harold Ballard(leafs) - Legendary in how awful he was.
Peter Karmanos(Carolina) - Intentionally tanked the team after he purchased it, to justify moving it out of Hartford.
Those are just off the top of my head.
Tons of owners out there were blackmailing cities during the arena mass builds between 1980 - > 2000, inspiration for the old Simpson monorail episode. Many of those teams in other leagues did in fact move.
There are many owners out there that never made the playoffs, let alone championships. Still more owners out there who were flat out frauds and charlatans, ending up in prison in several case. The NHL has had quite a few of those around due to lax background checks.
Sports history is long, and there were some truly horrible owners out there, and that doesn't even touch on the European sports/soccer leagues which I don't know much about. Katz isn't doing a good job, but he's not in the realm of "worst ever".