Tom Riddle’s middle name in J.K. Rowling’s Harry Potter series is Marvolo.
His full birth name is Tom Marvolo Riddle. He later rearranges the letters of that name to create the anagram “I am Lord Voldemort,” revealing the identity behind his chosen title.
Marvolo was the name of his maternal grandfather, Marvolo Gaunt. The Gaunt family claimed descent from Salazar Slytherin and valued its connection to pure-blood wizarding ancestry. Tom’s mother, Merope Gaunt, died shortly after giving birth to him.
The name is revealed in Harry Potter and the Half-Blood Prince. It is sometimes confused with Morfin, Tom’s uncle, or Merope, his mother; both are members of the Gaunt family but neither is Tom’s middle name.