Harry Potter and the Half-Blood Prince is a 2008 fantasy adventure film, based on the novel by J. K. Rowling. It is the sixth film in the popular Harry Potter films series. Production is in the post-production stage. David Yates, the director of the fifth film, Harry Potter and the Order of the Phoenix, is returning as director for this film. David Heyman and David Barron are producing the film, and Steve Kloves, though he did not write the fifth film, has returned as screenwriter for this instalment. Filming began on September 24, 2007 and the film is scheduled for a UK and US release on November 21, 2008, South Africa on December 5, 2008, and an Australian release on December 11, 2008. Like the previous film, the sixth film will be simultaneously released in regular theatres and IMAX 3-D.

On December 14, 2007, Warner Brothers released its official plot summary. It reads:

"Voldemort is tightening his grip on both the Muggle and wizarding worlds and Hogwarts is no longer the safe haven it once was. Harry suspects that dangers may even lie within the castle, but Dumbledore is more intent upon preparing him for the final battle that he knows is fast approaching. Together they work to find the key to unlock Voldemort's defenses and, to this end, Dumbledore recruits his old friend and colleague, the well-connected and unsuspecting bon vivant Professor Horace Slughorn, whom he believes holds crucial information. Meanwhile, the students are under attack from a very different adversary as teenage hormones rage across the ramparts. Harry finds himself more and more drawn to Ginny, but so is Dean Thomas. And Lavender Brown has decided that Ron is the one for her, only she hadn't counted on Romilda Vane's chocolates! And then there's Hermione, simpering[sic] with jealousy but determined not to show her feelings. As romance blossoms, one student remains aloof. He is determined to make his mark, albeit a dark one. Love is in the air, but tragedy lies ahead and Hogwarts may never be the same again.

Before David Yates was officially chosen to direct the film, many others had been offered the job, and previous directors had expressed an interest in returning. Alfonso Cuarón, the director of the third film, stated he "would love to have the opportunity" to return. Goblet of Fire director Mike Newell declined a spot to direct the fifth film, and was not approached for this one. Terry Gilliam was Rowling's personal choice to direct Philosopher's Stone. However, when asked whether he would consider directing a later film, Gilliam said, "Warner Bros. had their chance the first time around, and they blew it."

Yates has retained composer Nicholas Hooper, costume designer Jany Temime, visual effects supervisor Tim Burke, creature and make-up effects designer Nick Dudman, and special effects supervisor John Richardson from the fifth film. Since February 2007, Stuart Craig, the production designer of the first five films as well, has been designing sets, including the cave, and the astronomy tower, where the climax of the film takes place. Academy Award nominated Bruno Delbonnel is the film's cinematographer.

Yates and Heyman have noted that some of the events of Harry Potter and the Deathly Hallows may influence the script of the film, and that there will not be as many memories in the film as in the book. Yates noted: "We're making a decision right now to compress those a wee bit, but we've still got some really cool ones." Steve Kloves, who wrote the first four films, returned for the sixth adaptation. Rowling has read Kloves' script and crossed out a passage in which Dumbledore recalls a past female love, penning in the margin "Dumbledore is gay."

Filming began on 24 September 2007, with one week of rehearsals, and principal photography ended May 2008. Some sources stated that filming may move from the UK, where all of the previous five films have been shot. This is North Scotland reported filming will take place in New Zealand, due to the "more agreeable economy and climate" and lack of Scottish funding. The Sunday Business Post in Ireland has noted that the film's producers and WB executives have been scouting there, specifically Leinster and Munster because they "believe they have now exhausted possible locations in Britain." They are "particularly keen on Ireland, as the landscape is similar to Britain and will appear similar to the settings of the previous films." The crew also scouted around Cape Wrath in Scotland, for use in the cave scene. Filming is scheduled to return to Glen Coe and Glenfinnan, both locations that have appeared in the previous films, to preserve the continuity of the landscape.

On the weekend of 6 October 2007, the crew shot scenes involving the Hogwarts Express in the misty and dewy environment of Fort William, Scotland. A series of night scenes have been filmed in the village of Lacock and the cloisters at Lacock Abbey for three nights starting 25 October 2007. Filming took place from 5 p.m. to 5 a.m. daily, and residents of the street were asked to black out their windows with dark blinds. On set reports indicated that the main scene filmed was Harry and Dumbledore's visit to Slughorn's house. Further filming took place in Surbiton railway station in October 2007, Gloucester Cathedral, where the first and second films were shot, in February 2008, and at the Millennium Bridge in London in March 2008.

Though Radcliffe, Gambon and Broadbent started shooting in late September 2007, some other cast members started much later: Watson did not begin until December 2007, Rickman until January 2008, and Bonham Carter until February 2008. Principal photography wrapped up on May 17 2008.

The special edition two-disc DVD for Harry Potter and the Order of the Phoenix contained two sneak peeks of the film, while the US edition included an additional clip. Warner Bros and MSN will run an online Order of the Phoenix quiz, with the prize being a walk-on part in the film. As with the previous films, EA Games will produce a video game based on the film.