Blood Freak (1971)
A Vietnam vet meets a woman on the road and takes a job at a turkey farm, but after eating tainted meat and smoking marijuana, he becomes a turkey headed killer who craves blood.
Home Sweet Home (1981)
An escaped mental patient steals a car and finds a ranch with a family celebrating Thanksgiving. He then murders them one at a time as the unsuspecting family finds out too late that a killer is stalking them.
Blood Rage (1987)
During a night at the drive-in, a young boy murders a couple having sex and blames his twin brother for the crime. Ten years later, he resumes his murder spree after learning his innocent twin has escaped the mental home that he was institutionalized.
Intensity (1997)
A woman survives an attack by a serial killer on Thanksgiving only to be captured by him after she attempts to free another victim. Once in captivity, she plots her escape but learns he is not so easy to evade.
Alien Abduction (1998)
A found footage movie that features a family having an extraterrestrial encounter in their home as a family member videotapes a birthday party. Often claimed to be an actual event, the fictional movie predated The Blair Witch Project by ten years.
Hostile Takeover (1988)
During a Thanksgiving weekend, a group of people working together is taken hostage by a coworker who has no demands. What unfolds is a mix of office politics and tensions held by the staff as the police try to negotiate the release of the hostages. 
Boogeyman (2005)
After witnessing his father being taken by the boogeyman as a child, a young man lives in fear that the same creature will take him. After a Thanksgiving dinner with his girlfriend's family, he returns to the psychiatric ward he was treated to learn the same boogeyman may haunt a young female patient.
Poultrygeist: Night of the Chicken Dead (2006)
A chicken restaurant built on a Native American burial ground disturbs the spirits of the dead, who then possess the patrons by turning them into chicken like zombies. Although not a Thanksgiving movie, it's only fair to include a Troma movie in this list.
Seance (2006)
A group of students staying in a dormitory over the Thanksgiving holiday holds a seance, and bad things happen. Their attempt to contact the spirit of a dead girl instead summons her killer.
ThanXgiving (2006)
A group of film students venture into the woods to film a movie and find the perfect location in an abandoned campground. Yet the film crew is not aware of the horrors that await them.
Grind House: Thanksgiving Preview (2007)
A gory movie preview that was shown during the movie Grindhouse features a mysterious killer who is targeting people who are celebrating Thanksgiving in Plymouth, Massachusetts. It would have made a great holiday horror film if it was real.
Home Movie (2008)
A series of home movies document the descent into darkness for the Poe family and what happened to them at the hands of their children. What starts as the perfect family in a remote upstate New York home takes a shocking turn as the children are shown to be hiding something from their parents.
ThanksKilling (2008)
A sarcastic killer turkey named Turkie is awoken and attacks a group of college students who camp near his burial site. As the teens try to stop the killer poultry, he makes quick work of them with bad jokes and puns.
Kristy (2014)
A struggling college student decides to stay on campus during the Thanksgiving break and finds herself the target of a bizarre cult. As she tries to look for help, she will have to defend herself as the cult invades her campus and cuts off all her means of escape.
The Oath (2018)
An interracial couple celebrating Thanksgiving is pressured by family members to sign a loyalty oath. As family members offer their opinions on the matter, a couple of government agents arrive as society appears to be in revolt over this measure.