well, they have 3 immortal breeds (vampires, lycans, and one singular uberhuman) and mere humans.
a hybrid combines one or more of the immortal strains.
an ultimate hybrid would combine all four bloodlines, I would think.
dude, Underworld and UW2 are gooooooood movies. I recommend them to you. see 'em.
My dragon is a hybrid.
I'm not sure how he would fare against your Underworld characters, but he has some healthy defensive capability.