Instagram/Ralph Fiennes & Tilda Swi Celebrity Ralph Fiennes suggests Tilda Swinton as Voldemort for HBO's Harry Potter series. Discover his full casting thoughts. April 13, 2026 AceShowbiz - Ralph Fiennes, famed for his role as Voldemort in the Harry Potter film franchise, recently shared his thoughts on who should portray the dark wizard in HBO's upcoming series Harry Potter and the Philosopher's Stone. During an appearance on BBC's The Claudia Winkleman Show, Fiennes was asked about the casting of Lord Voldemort, a role that remains unfilled for the new adaptation.