The Sinister Six? More like Sausage Fest Six.
Grim Huntress aka Kraven the Hunter aka Anastasia Kravinoff
Powers/Weapons: Super strength and super speed, she is a highly trained martial artist and expert hunter.
Backstory: Daughter of the original Kraven the Hunter, Anastasia grew up hating Spider-Man and that hatred only burned brighter when she blamed the webslinger for her father's suicide. Taking up his mantle, she swears vengeance.
Reason She'd Be An Awesome On-Screen Baddie: A take-charge female in practical combat armor with a blood debt against Spidey and a off-kilter view seeing him as the villain and herself as the hero? Yes please. It'd be so easy to bait-and-switch her in. After all she technically IS Kraven the Hunter when her father is dead and Grim Huntress while he is alive.