Carnivorous plants are popular feature
s in science fiction
. Although real ones generally eat only insect
s, those in sci-fi
are often capable of eating full-grown human
s or more.
One example from fantasy is the tangle tree in Piers Anthony's Xanth world. It looks like a nice, shady place to rest, but it has tentacles that grab unsuspecting travelers and pull them into its mouth.
There are also sentient (or more accurately sapient) and mobile carnivorous plants in sci-fi. These include Lyekka from Lexx, who lives in a pod and emerges once in a while to absorb some animals for protein. She is not evil, just carnivorous.
Another is Pa'u Zotoh Zhaan from Farscape. She is in most ways a typical walking, breathing person like all the other aliens on the show. She eats a varied diet, including both plant and animal matter. But her species, Delvians, are actually flora-evolved. The one situation under which they actually need animal protein is after a period of starvation. If this occurs, they begin to produce spores (possibly a reproductive act, because stationary plants on earth tend to produce more seeds/spores during a drought). After even longer without food, they start to grow poisoned spikes in preparation for a dormant state. In this state, they look like any mass that might grow on a forest floor. But when an animal comes close enough, these spikes will be launched, knocking out the animal and awakening the Delvian, who can then eat the animal and become active again.