Harry Potter and the Half-Blood Prince is a 2009 fantasy film directed by David Yates from a screenplay by Steve Kloves. It is based on the 2005 novel Harry Potter and the Half-Blood Prince by J. K. Rowling. It is the sequel to Harry Potter and the Order of the Phoenix (2007) and the sixth instalment in the Harry Potter film series. It stars Daniel Radcliffe as Harry Potter, alongside Rupert Grint and Emma Watson as Harry's best friends Ron Weasley and Hermione Granger respectively. The story follows Harry's sixth year at Hogwarts as he receives a mysterious textbook, falls in love, and attempts to retrieve a memory that holds the key to Lord Voldemort's downfall.

Filming began on 24 September 2007, leading to the film's worldwide cinematic release on 15 July 2009. With an estimated budget of $250 million, it is one of the most expensive films ever made and the most expensive film in the Harry Potter film series.

Harry Potter and the Half-Blood Prince was released in 2D cinemas and IMAX formats in the United Kingdom and the United States on 15 July, by Warner Bros. Pictures. The film received positive reviews, with praise for the story, emotional weight, cinematography and performances. It was a major commercial success, breaking the record for the biggest single-day worldwide gross with $104 million. In five days, the film made $394 million, breaking the record for highest worldwide five-day opening. With a total gross of $941 million, it is the second-highest-grossing film of 2009. The film was nominated for many awards, including the Academy Award for Best Cinematography and the BAFTA Award for Best Production Design and Best Special Visual Effects.

It was followed by Harry Potter and the Deathly Hallows – Part 1 in 2010.