The Sarlaac is featured in the first act of Star Wars Episode VI: The Return of the Jedi.  It’s a multi-tentacled creature whose jaws are lined with razor sharp teeth.  It lives in the Great Pit of Carkoon on Tatooine, which is hollow in the desert floor.

 

In the film it’s chosen as a method of execution for the rebels caught in Jabba the Hut’s palace.  As the rebels mount an escape, several of Jabba’s entourage fall into the Sarlaac and despite a close call for Landon Calrissian, the rebels escape unscathed.