Simon Bar Sinister

Underdog was a show about a clean-cut do-gooder pup who popped a pill from his secret ring whenever duty called. The ring would transform him into a superhero of epic proportions who could fly and save the day. More often than not, this meant saving his girlfriend. Basically it's a canine superman cartoon clone. I don't remember much about Simon, but I do remember that he was the main supervillain and the most evil guy on the whole show. But that's kind of obvious, really. I mean just look at those eyebrows! Sinister is an understatement!