The Damned Thing is a monstrosity and the main antagonist from the story "The Damned Thing" by Ambrose Bierce and it possessed and murdered a man. It later appeared in the Masters of Horror TV adaptation of the same name, committing far more murders and possessions.
Ambrose Bierce Short Story
In Bierce's short story, the Damned Thing first appears during William Harker's explanation about the circumstances surrounding the death of Hugh Morgan. During a hunting escape, a mysterious and unseen entity moves through the wild oat. While Harker has no reaction, Morgan draws his gun and shoots at the entity. Suddenly, Harker is thrown back by an unseen force and witnesses as Morgan is violently shaken while he cries in agony. Eventually, the Damned Thing kills Morgan but Harker's report is dismissed and it is assumed that a mountain lion had done the deed.
Masters of Horror
In the small Texas town of Cloverdale, Sheriff Kevin Reddle has a tragic past where his father had gone berserk, murdered his wife, and was then violently destroyed by an unseen force. His father refers to the creature as "the damned thing" shortly before death, fearfully noting that it had found him.
A grown-up Kevin remains in Cloverdale and conducts constant surveillance of the town for signs of the entity's presence. This puts a strain on his relationship with his wife Dina and their son Mikey who leave Kevin. Unfortunately, a series of berserk murders occur, including the town priest who murders under possession of that same "damned thing". Kevin searches into the town's past and finds that a similar collection of possessed murders had occured before when an oil well was drilled. This leads him to the conclusion that the Damned Thing now seeks to kill him and he tries to get to his family before it can.
The Damned Thing influences Dina and almost drives her to kill Mikey until Kevin stops her. Unfortunately, the madness influences Kevin and he is about to kill his family when the Damned Thing appears. It rises from the earth as a mud/oil monstrosity and swallows Kevin. Dina and Mikey flee but are attacked by the Damned Thing at the last second, presumably killing them.