Watch Underworld full movie online 123 Movies. Watch Underworld 123movies online for free. Underworld Movies123. Vampires and werewolves have waged a nocturnal war against each other for centuries. But all bets are off when a female vampire warrior named Selene, who's famous for her strength and werewolf-hunting prowess, becomes smitten with a peace-loving male werewolf, Michael, who wants to end the war.