Murder of the Riddle family

The Murder of the Riddle family was committed by the future Lord Voldemort in 1943, when Riddle ventured to his parents' hometown of Little Hangleton in order to learn more about his heritage. When Riddle learned from his maternal uncle Morfin Gaunt that the former's father was a Muggle, the younger Riddle proceeded to the Riddle Manor and killed his father, paternal grandfather, and grandmother with the Killing Curse. The next morning, the rest of the villagers were genuinely stunned by the killings, despite their general disgust with the Riddle family.

This massacre turned out to be a pivotal event in Wizarding history, as this was the first known murder that Riddle had committed. In addition, the deaths of the elder generations of the Riddle family would become the prelude of the anti-Muggle campaign that the youngest Riddle would lead as Lord Voldemort.

Over half a century later, Voldemort returned to the Riddle House while being tended to by his servant Peter Pettigrew while discussing the former's return. When Voldemort's plan came into fruition roughly a year later, Pettigrew used some of the bones of Tom Riddle, Sr. as part of an ancient potion that returned the Dark Lord to his former glory. Immediately afterwards, Voldemort told Harry Potter, who was kidnapped as part of the same ritual, about how he killed his (Voldemort's) father and paternal grandparents.