I'd have to be Morrowwind, after finding an unlimited money loophole (barter was good enough to buy things at less than I sell them for, so I essentially had unlimited money), unlimited potential for items (some merchants instantly restocked their items, including the 500 mushrooms I just sold to them), and Alchemy.
Intelligence makes your Alchemy Potions better. So I made a batch of intelligence potions, drank them all, and made some better ones. Drank those, made some even better ones, etc etc.
Eventually I had about 500,000,000,000 or so intelligence (normal max of 100, I think), and made potions that granted around 50 trillion of a stat for about 8 hundred years.
Was all fine and dandy, except my strength was so high I instantly broke ANY weapon I swung. It took a long time for me to come back down when I jumped (cource the fall couldn't touch my ungodly amount of health), and I held onto my speed potion until I was done having fun. Then I saved, drank it, and cautiously pressed the "forward" button, promptly crashing my computer, probably as it was trying to figure out how many times I just ran around the world in a microsecond.
I felt a little OP at that point.