Martin Prince Sr. is Martin's father.
Martin Prince Sr. is the father of Martin Prince, and he was the husband of Martha Prince. He is a stock broker in Springfield and was shown bringing his son to work on "Bring Your Child to Work Day", where Martin made over $1 million trading soy futures (and subsequently lost all but $600). He appears to be a nerd much like his son, seeing as he has somewhat of a lisp. Martin Sr. was also one of the fathers that went in Ned Flanders's RV, to find their sons in Shelbyville. In another episode, when he and Martha send Martin off to Kamp Krusty, he sugarcoats by calling where his son will be going an "image enhancement camp", but Martin sees through this and knows better for a fact that it's a fat camp. When Martin's party guests get upset stomachs from eating diseased oysters, sure enough, just as he thought that this would happen, he knew that it was a bad idea, as he tells his wife they should've served cake instead. Later in the same episode, they're seen outside the school with other parents and residents when the building is put on lock down.
- He took a real estate license along with Luann Van Houten, Sea Captain and Marge Simpson.
- In The Simpsons Game, he can be seen walking around the hub. He can be heard saying that he is surprised that his tooth fillings pick up not only radio, but specifically Mexican radio.
Note: Many of his appearances are brief background roles. Episodes in which he has an actual role are in bold.