Fit-Fat Tony

Fit Tony is Fat Tony's cousin from San Diego. The only physical difference between him and Fat Tony is that he is (or was) in excellent physical condition.

History
Fat Tony dies of a heart attack and Fit Tony takes his place running the Springfield mafia. The pressures get to him, so he starts to eat and gains weight. Soon he is known as Fit-Fat Tony -- then just Fat Tony, for short. At that point, he's identical to Fat Tony.

Thus, it is as if Fat Tony never died, and all appearances of Fat Tony -- subsequent to the Donnie Fatso episode -- are actually of Fit Fat Tony, similar to the situation of Snowball II and Snowball V or Armin Tamzarian and real Seymour Skinner.

While his cousin Fat Tony was a widower, Fit Tony (now called Fat Tony) -- who is married -- takes on Selma Bouvier as his formal "goomar" (mistress).

In Penny-Wiseguys, Fit Fat Tony gets jury duty -- so he names his accountant, Dan Gillick, temporary don. Gillick proposes to Tony to save money by getting rid of redundant mobsters -- but he's mortified when Tony tells him to rub them out. He finds he likes it way too much, and asks Homer to stop him from killing mob members.