Salvatore Valestra was once the most powerful and prominent gangster in Gotham City and ruled the city's underworld with an iron-fist alongside his chief-lieutenants Chuckie Sol and Buzz Bronski. About a year before Batman first appeared in Gotham, Salvatore loaned money to the businessman Carl Beaumont but despite promising he could, Carl was unable to pay Valestra back. Not long after Carl's daughter Andrea got engaged to her sweetheart Bruce Wayne, Carl had both of them flee the country to Europe in order to escape Valestra's wrath.
Valestra managed to hunt down Carl however by bribing Beamont's assistant Arthur Reeves into ratting out Carl's location as Arthur was short on the funds he needed to run as Gotham City Councilman. After extracting the information Valestra sent his top hit-man out to kill Carl, a gangster named Jack Napier who was successful in his mission.
Many years later Valestra lost his grip on Gotham's criminal underworld to new gangsters like Penguin or Two-Face with his former enforcer Jack Napier now being the Joker and Salvatore himself suffering from respiratory problems due to his smoking. At one point Sal became especially concerned for himself as his two former business partners Chuckie and Buzz had been murdered, apparently by the Batman but in reality by Andrea Beamont under the alias of "The Phantasm". Fearing that he was next to be killed, Salvatore hunted down his old hit-man the Joker to help protect him from who he thought was Batman. Joker was impossible to persuade to his side so in a fit of rage and desperateness, the elderly Salvatore grabbed Joker's collar to give him his command. As revenge for the action, Joker murdered Valestra with his signature Joker Toxin and left the corpse in Valestra's appartment as bait for the murderer to further his own scheme.
- It is possible that (similar to Roland Daggett who was based on Max Shreck) Sal Valestra was inspired by the Burtonverse character of Carl Grissom from the 1989 film. Both characters are aging crime-lords that were Gotham's kingpin in their prime and who were employers of Jack Napier before he became the Joker and both characters were ultimately killed by Jack after he became Joker.
- Valestra's first name being Sal is possibly an allusion to the character of Sal Maroni, a prominent Gotham gangster that was replaced in the animated series by Rupert Thorne.
- Valestra is briefly mentioned in the Elseworld story Batman: White Knight where his gang is one of many taken over by Jack Napier in his political-scheme to make Gotham City a better place.