Question: Who is Harry Potter and Albus Dumbledore's shared nemesis?
Sentence (from "Harry Potter and the Half-Blood Prince"): Set during protagonist Harry Potter's sixth year at Hogwarts, the novel explores the past of Harry's nemesis, Lord Voldemort, and Harry's preparations for the final battle against Voldemort alongside his headmaster and mentor Albus Dumbledore.
Relevant evidence: Yes