Heihachi Mishima from Tekken is pretty much the biggest bastard in the gaming world, he is the epitome of that term in my opinion.
For example he brutally beats his own son the age of 6 (approx) and then throw's him of a cliff, to test if he has the strength to survive. His supremely cruel treatment of Kazuya is right up there and leading that character to become corrupted by evil and becoming an absolute bastard in his own right.
After Kazuya takes some good old fashioned revenge and throws him off the same cliff in tekken 1, Heihachi returns in tekken 2 and taking advantage of his son who is battling some major spirtual conflict within him and thows his unconcious body into a volcano.
Later down the track he betrays his own grandson Jin and shoot's him in in the back of the head (end of tekken 3)
In each installment, Heihachi is seen to kill his own family members in increasingly more inventive ways.
ABSOLUTE BASTARD!