Old Monty Hewitt is Luda May Hewitt's brother and the uncle of Leatherface and Sheriff Hoyt. Monty is portrayed by Terrence Evans in both movies.

Monty Hewitt (also known as Old Monty) appears as a bitter, lecherous old man with two amputated legs, who permanently uses a wheelchair. After Sheriff Hoyt kills a biker's girlfriend, the biker seeks revenge on the Hewitts and attacks Monty by shooting him in the leg with a .357 magnum. As a bit of impromptu "surgery", Hoyt orders Leatherface to remove the wounded leg with his chainsaw. Leatherface accidentally nicks Monty's second leg, so Hoyt tells him to remove that as well to lower the risk of infection, and for "balance".[11] Before his accident, Monty worked as a tow truck driver, which is seen in the prequel.

Old Monty has an unnamed pet dog and is the third member of Leatherface's family to meet the stranded teenagers in the first film who eventually become Leatherface's victims (the first being Luda May and the second being Jedidiah Hewitt) and he is the one to first summon the killer by repeatedly tapping his cane against the floor.[4] His exact role in the family is still unclear, with various people on the film speculating that he is either Luda May's husband or brother (or both), though Luda May and her children act like it is her brother. In The Texas Chainsaw Massacre: The Beginning (2006) Monty shows he has hardly any interest in killing innocent people and also claims he wants nothing to do with it. Yet later on Monty seems to have become a lot more bitter and hateful towards outsiders.[14] It is also implied in the films and comics, that over time Monty became more of a sexual predator/parahiliac as his family's killing spree began to increase. In the novelization of the 2003 remake, Old Monty is presented as Thomas Hewitt's father and Luda May's husband, the nature of his leg injury is also different from the one shown in the 2006 prequel, in the novel, a young Leatherface chops his abusive father's legs off with a cleaver, however it states in the novel that Monty sees his son's actions as the proudest moment of his raising of the boy.

In The Texas Chainsaw Massacre comics by Avatar Press, set between the events of the remake and prequel, Monty appears as a prominent character; the Avatar Press comics depict Monty as somewhat more depraved and vicious then the films, with the 2006 miniseries The Texas Chainsaw Massacre: The Grind having him strangle a girl to death and later attempt to rape the girl's foster sister, who escapes by punching Monty in the head repeatedly after freeing herself from the restraints he has her in.[24]