Which Harry Potter book has the subtitle “The Half-Blood Prince”?

The Harry Potter book with the subtitle “The Half-Blood Prince” is Harry Potter and the Half-Blood Prince.

It is the sixth novel in J.K. Rowling’s seven-book series and was published in 2005. The story follows Harry during his sixth year at Hogwarts while Lord Voldemort’s return becomes an increasingly open threat to the wizarding world.

The Half-Blood Prince is an identity revealed within the plot. The title refers to a former Hogwarts student whose handwritten notes improve Harry’s performance in Potions. The mystery surrounding those notes develops alongside lessons about Voldemort’s past and the Horcruxes.

The novel is sometimes confused with the sixth film, whose full title is Harry Potter and the Half-Blood Prince. The film was released in 2009, four years after the book. Both versions feature Professor Horace Slughorn and the investigation into Voldemort’s history.