Kazuya Mishima

I think Kazuya Mishima has to be Tekken's most unique character- he was the protagonist in Tekken 1 and he became a recurring antagonist in the later series. Somehow, this made him popular. So what's the big deal? He was starting of as a frail child much to the frustration of his father Heihachi Mishima so he got thrown from the cliff by his despicable father. Down there, he nearly died but the Devil gene triggered. So he entered into the first tournament much to the pleasure of his father. He won the tournament and threw his father off the cliff and took over the Mishima Zaibatsu.

However instead of righting the wrongs, he under the influence of the Devil gene within made the Mishima Zaibatsu more corrupt. He through the technology of the company had created biological weapons like Roger and Alex. Also, he had entered into a meeting with Jun Kazama, who he had raped out of his insanity. From that rape came his son Jin Kazama. His father Heihachi Mishima whom he tossed down the cliff defeated him when his Devil gene went out of control. He was thrown into a volcano but he was brought back by G-Corporation and he went into hiding for an indefinite amount of time.

In Tekken 4, he returned seeking revenge against his father Heihachi Mishima in an endless cycle of revenge. However he had the hindrance of his son Jin Kazama who also held the Devil gene and he sought to get the full power. Although it seemed he and his father Heihachi Mishima would reconcile after he was defeated by Jin Kazama, however he double-crossed his own father by using some exploding Jack robots. He transformed into Devil Kazuya and fled the Honmaru leaving his father alone which was just before Tekken 5.

In Tekken 5, he was after power and more power and later in Tekken 6, he took over the G-Corporation as its head. He soon fought with his son Jin Kazama in a corporate way- G-Corporation vs. Mishima Zaibatsu. He offered a handsome cash reward to anybody who would bring his wayward son alive to him. He entered into the Tekken 6 tournament but his outcome is unknown as of right now.