Milton Farnsworth Thatherton is a former employee of Strickland Propane who strikes out on his own and opens up the crooked Thatherton Fuels company across the street from Strickland. He dresses like an old school rich cowboy with a ten-gallon hat and cowboy boots and a walrus-style mustache. An untrustworthy type, Thatherton is a sometime foil to Hank Hill and/or Buck Strickland. Whenever Thatherton does something devious, or even merely at the sight of him, Hank or one of his family members is usually heard exclaiming "Thatherton!" (similar to "Newman!" in Seinfeld). At one point, Hank, when trying to entice an obnoxious potential customer, implied the true meaning of "M.F." in Thatherton's name before having Thatherton interrupt him by saying "My friend!"
- Milton Thatherton has many of the same bad qualities as Buck Strickland, such as betting away his employees in card games or womanizing. However, his vices are more pronounced than Buck's. For example, after Buck lost a poker round to Thatherton, he sent away Hank to work for Thaterton Fuels to cover his bet. At Thaterton Fuels, Hank saw even worse deception than Joe Jack attempted on customers, and could not bring himself to flimflam a customer. Thatherton berates Hank for the blown sale by saying that he cost Thaterton a jet ski payment, showing that Thaterton sees his customers as people solely to provide revenue, as opposed to Hank, who wants to give honest goods and quality service in return for the customer's dollar. Thatherton is also overt about the theory that "sex sells", hiring beautiful women such as centerfolds or Hooters girls to gussy up his business and believing that mediocrity gains new credentials through gimmickry, glamour and glitz.
- According to the episode Lost In Myspace Thatherton is obsessed with the American rock band Weezer.
- In the episode The Company Man, it's revealed that Thatherton is the only man ever censured by the Texas Propane Commission for lewdness and conduct unbecoming of a propane salesman.
- Thatherton seems to represent a longtime Texas saying of "all hat no cattle", which was attributed to owners of rundown ranches who had few, if any, livestock but wore ten-gallon hats and other attire to try and dazzle the general public into thinking they were successful. In the same manner, Thatherton Fuels is regarded as second-rate by many businessmen in Heimlich County.