It occurred to me that the best type of villain is the type that constantly makes the hero’s life completely miserable. With this in mind, all villains can take a chapter out of this one’s maniacal conquests. The one who was there before us, and who will still be there long after we all die, because he knows when to "hide in his shell," as it were. This villain is owed a great debt by all villains after him, for he has weathered the ages, stood the test of time, and STILL cannot hang onto his captives.
Machinoids, Bowser is possibly the most disappointing villain of the entire video game world. Not only was he there first to set the bar, he set it rather low. He put his own children in the way of a certain meddlesome plumber loaded up with mushrooms before he would even make an appearance. I will give him this: He certainly knows how to hide very well.
When Bowser made his move, the Mushroom Kingdom became infested with Goombas, Bob-ombs, and other insidious creatures which made Mario's journey that much more harrowing. Granted, Bowser did wise up after their first encounter and stopped putting himself on collapsible drawbridges, but instead of mechanizing the citizens of the Mushroom Kingdom and sending them after that short Italian guy (who is also bald, why do you think he wears a HAT??) he keeps sending the same baddies.
It is in my humble opinion that Bowser should be looked upon as the greatest failure of ALL video game villains, because there was actually a time where he HELPED his enemies achieve their goals and save the day. I wish simply for the sake of villainy that heroes and villains would NOT work together honestly to achieve an end.
If there were an award for worst villain because of turning your back on all that is evil and treacherous, Bowser would be top contender. For all else, he is a whining failure.