Freyja: I don't know much about Norse mythology except that I am deeply committed to Chris Hemsworth's take on Thor, but I will be learning more for my books. Freyja is seriously awesome. She's not only associated with death, but also love, sexuality, beauty, fertility, gold, and war. This hot mama has been depicted in a cloak made with feathers, a warrior's outfit with leggings and chainmail, and a sword. All you cat lovers and cat owners, her chariot is drawn by cats in many drawings. This could be a fairly easy costume to put together if someone were to piecemeal the parts from their own wardrobe and Halloween shops like Spirit Halloween or Party City.
Santa Muerte isn't just a deity, she's actually a Mexican folk saint, and she's venerated. She's often depicted with a cloak and scythe, and sometimes with black angel's wings. See why I want to be her for Halloween?