****! I love them both, for different reasons! Marik for being a bad ass, Pegasus for being a creepy psycho and owning the ****en game. I can't choose.
The whole Marik era made Pegasus' era look child's play. Marik was so ruthless with his mind control and the Egyptian god cards. And then when his DARK SIDE came out, >>>>>>>>>>>>
Evil Bakura gets an honorable mention too, especially since he was the final villian in the whole series.