Light Yagami is the main character from the anime Death Note. Light is a bored genius with a powerful notebook that you don’t want to find your name in. To get the look you’ll need a brown wig that looks like early John Lennon, the red tie, sportjacket and brown/grey slacks.
Light’s look is something of an average businessman (or 80s newspaper reporter) so you may already have some of his look in your closet. That is a good way to save a dollar or two.
Or you can get the all-in-one costume here.
Check out Light’s nemesis L.