Who is Voldemort's child?
Delphini (born c. 1998), known by the nickname Delphi, was a British half-blood Dark witch, the daughter of Tom Riddle and Bellatrix Lestrange. Being the only child of Lord Voldemort, she was able to speak Parseltongue, and she became the only known living heir of Salazar Slytherin after the demise of her father. How did Bellatrix and Voldemort have a child? Yep, that happened: Bellatrix and Voldemort had sex sometime around Order of the Phoenix or Half-Blood Prince, and their wild night in bed led to a child named Delphi Diggory/Riddle/Lestrange.