Wearing black as a sign of how cool a character is, or wants to be.
Important: This seems to actually cover three tropes: Wearing black to look cool (or at least attempt to), wearing black to show a character is an oddball (like goths or Ian Malcolm of Jurassic Park), and black as an Anti Hero color (like Blade). Should I split this into those? Note: Since this doesn't rely on Willing Suspension Of Disbelief, this will not be listed under Rule of Cool. It will be listed under The Utterly And Completely Definitive Guide To Cool though.
One of the ways to show a character is cool, or is trying to be cool, is to dress that character largely in black. Why? Well it could be because black represented evil and danger, but some people think Evil Is Cool. Or it could be because some nonconformists like to wear that color, and others saw those people as cool. Whatever the reason, black is now often ways to make people look cool, especially black Cool Shades and a black Badass Longcoat. A Goth or rebellious teen usually dresses in black because of this trope. A Woman In Black often follows this trope. As do The Men In Black. This is often the reason for the trope Movie Superheroes Wear Black. A Sister Trope to Black Cloak, Black Bra And Panties, (such clothes being considered sexy), Little Black Dress (a dress that is considered always stylish), Black Swords Are Better. Compare Purple Is Powerful, Red Is Heroic. Constrast Woman In White, Man In White. Please do not list characters that just wear black, and you think are cool.