Susan Cummings (born c. 1959) is a billionaire American woman who was convicted of killing her boyfriend, Argentine billionaire Roberto Villegas .

Cummings inherited her fortune from her father, former CIA agent turned arm dealer Sam Cummings . A horse lover, Susan lived a lavish lifestyle, owning her own horse farm and being a well known Virginia socialite. Cummings, however, was also a very shy person: She did not enjoy partying as much as other billionaires would, and she was devoted to her horses. As a matter of a fact, she preferred being with her horses than doing anything else someone in her economical position could do.

Villegas felt attracted to the young heiress as soon as they met. An avid polo player, he befriended Susan, while at the same time, gaining a spot among Virginia's high society's socialites. Soon, the couple of friends began dating, which later on lead to Villegas and Cummings moving together.

On September 7 of 1997, Cummings placed a call to the 911 emergency service number, claiming that she had shot her boyfriend in self defense. According to her, he had turned abusive towards her, threatening to kill her with a knife.

According to police reports, Roberto Villegas was found with a knife crossing his arm. Susan Cummings presented some minor cuts, which the police suspected were inflicted by herself to make the circumstances look like they actually happened the way she told them. Cummings received medical attention for her cuts, and was arrested on charges of homicide.

The trial that ensued proved to be scandalous, especially among Virginia's socialite classes. Opinions as whether she was guilty or not were divided, as many of her friends and acquaintances could not believe that the usually shy, horse caring Cummings could not be a murderer. Cummings' defense lawyer had also defended Lorena Bobbit.

Noting that when the police found Villegas' corpse he had a piece of food inside his mouth, the jury found Cummings guilty, but her charge was reduced to voluntary manslaughter. Cummings spent sixty days in jail and paid a $2,500 dollars fine.

In 2004, writer Lisa Pulitzer wrote a book which was entirely devoted to Susan Cummings and the death of her boyfriend Villegas.