You can get the complete Ryuk costume here. The key to the Ryuk costume is the unique, black winged outfit, the light blue body paint and the crazy shinigami eyes. They’ll custom-make the costume to fit you.
I am a huge fan of the anime Death Note. (Check it out on Netflix if you haven’t seen it yet). My favorite character is Ryuk, who is a shinigami (kind of like a demon). He is funny, powerful, and addicted to apples.
Check out Light and L cosplay from Death Note.