8. The Sarlacc Pit
What you see in the films: The Sarlacc Pit is not actually a character, no. However, the creature called a sarlacc who inhabits the Pit of Carkoon is. We see it in Return of the Jedi, trying to snatch and eat Luke Skywalker and the others. Tossing enemies into the Pit of Carkoon to be eaten by the mighty sarlacc is a favorite pastime of Jabba the Hutt, as indicated by his enthusiasm.
The expanded backstory: A debate rages among scientists with regard to the taxonomic classification of the sarlacc. Some argue that the sarlacc are arthropods, like a crab or a scorpion. Other classify them as a plant, due to their anchored roots and the fact that they reproduce via spores. The spores travel through the air and eventually make their homes in otherwise inhospitable and harsh locations. Its entire body is buried underground, what we are seeing is only its mouth.