Grandpa Slaughter appears in The Texas Chain Saw Massacre, and its sequel Texas Chainsaw Massacre: The Next Generation portrayed by John Dugan and Grayson Victor Schirmacher respectively and appears in more of the franchise than any other character besides Leatherface. He is a supercentenarian, former butcher/slaughterman and implied mass murderer.
Snippets of Grandpa's history prior to the events of The Texas Chainsaw Massacre films occur throughout the series; it is revealed that Grandpa was originally a worker at a slaughterhouse whose skills at killing and butchering cattle were unmatched. After modern machinery was implemented at abattoirs for butchering animals, Grandpa retired from his work, ashamed. Even decades later, the Sawyer descendants regarded slaughterhouse machinery with disdain. Grandpa apparently settled down with the unnamed Grandma and began a family, the cannibalistic Sawyers (how they became cannibalistic is never revealed, though it is implied that they resorted to cannibalism in order to survive starvation, because the family was already poor when Grandpa and the rest of his family quit working).
In The Texas Chain Saw Massacre, the 124-year-old Grandpa (John Dugan) appears as a somewhat minor character, initially thought to be already dead; he is first seen briefly during Leatherface's chase scene, Sally approaches him seeking help but assumes he is dead when she sees how old he is. Later after heroine Sally Hardesty (Marilyn Burns) is captured by his grandchildren, W.E. (Jim Siedow), Leatherface (Gunnar Hansen) and the Hitchhiker (Edwin Neal), Grandpa is taken from the second floor of the house and brought to her by them. Leatherface proceeds to slash Sally's finger and forces it into Grandpa's mouth, so he can suck her blood (proving that he is, in fact, alive), an event that causes Sally to fall unconscious. Some time after Sally is awakened, Drayton, Leatherface and the Hitchhiker decide to allow Grandpa to end her life through the use of a hammer; due to his advanced age, Grandpa is largely incapable of using the hammer efficiently and continues to drop it, although one hit does leave Sally with a large visible wound on her head. The hassle that ensues with Grandpa's continued dropping of the hammer and his grandchildren's over-eagerness to help him allows Sally to break free of the Sawyer family and jump out a window, though he and Drayton do not attempt to follow her.
In the 1994 film Texas Chainsaw Massacre: The Next Generation, Grandpa (Grayson Victor Schirmacher) appears as a member of the Sawyer family. The scene starts off similar to the original film's dinner sequence, until the family's screaming and bickering cause the lead character to snap and start yelling and berating them as though she were in charge. The chaos causes Grandpa to show much more life than he showed in the 1974 film, as he opens his eyes, visibly reacts in annoyance to all the yelling and chooses to simply leave the dining room rather than put up with any more of his family's antics, not even wanting anymore to participate in the implied 1973-style sacrifice that was meant to occur but was never started.