Audrey II was the main antagonist in Frank Oz's 1986 musical movie Little Shop of Horrors.
At first appearing to be little more than a harmless Venus Flytrap-type plant, after Seymour started to feed it blood (his own and others), Audrey II soon grew into a great, tentacled monster complete with enormous, fang-filled maw. Audrey II also showed the ability to reproduce on its own, growing smaller "buds" along various portions of its appendages.
While out on Skid Row, Seymour came across an unusual plant, the likes of which he'd never seen before. Taking the plant back to the flower shop where he worked, Seymour quickly found out that the plant could only survive on blood. Human blood, to be precise.
As the plant grew in size, requiring ever-larger quantities of blood, Seymour was forced to go to greater and greater lengths to keep it fed, eventually resorting to feeding it people.
Finally discovering that the "plant" is actually an alien creature intent on overthrowing the Earth and repopulating it with it's own offspring, Seymour battles Audrey II, eventually managing to kill it through electrocution. Audrey II has, however, already managed to spread at least one of it's seeds to another location . . .