THAT'S NOT DEXTER. Please... lets be a bit more interesting than that please.
Mine has to be Charles Lee Ray/Chucky, from the Childs play/chucky series of movies.
He's incredibly witty, funny and is a text book psychopath. He is very clever, very in tuned with his senses, knows how to use his environment, but ends up fucking himself over by losing control of his rage sometimes.
He'll be pwning someone with clever movement and pre-planning, then randomly just charge at someone who has a gun or an advantage over him. He fights until his body is completely broken.
I love his first lines in the first movie when the mother forces him to reveal himself.
"You stupid bitch, you filthy slut, I'll teach you to fuck with me". That was just fucking awesome. The dolls face turning from a neutral, expressionless face to a demonic, hate filled, terrifying face.