Digestive system
Owen Harper's digestive system shut down following his death and partial resurrection. As a result, he could not eat or drink. (TV: Dead Man Walking)
Abzorbalovians would absorb their victims into their bodies, with their victims' faces becoming embedded into their flesh while being slowly digested alive, with the Abzorbalovian feasting on their victims' minds and compressed bodies. The process took a fairly long time, as Bliss, who was absorbed into the Abzorbaloff's right buttock, was still alive and being digested weeks after being absorbed. This process also caused them to fart often and their stomachs to make gurgling noises constantly. (TV: Love & Monsters)
Raxacoricofallapatorians had varying digestive systems according to family: A Slitheen noted the Hazrateen to have superior tastes which allowed them to enjoy the richest of foods, while the Blathereen were content with lower grade products. (AUDIO: The Taste of Death)