Diamondback is the name of two Marvel Comics supervillains, one male and one female. The male Diamondback, Willis Stryker, is a character in Marvel's Luke Cage. He is a master knife thrower, and is armed with a wide variety of high-tech knives. He also wears a protective suit which gives him super-strength.
The female Diamondback, Rachel Leighton, appeared in Marvel Disk Wars: The Avengers. She does not have superpowers, but she has an arsenal of high-tech diamonds and is a skilled martial artist and tactician, and a brilliant criminal mind.