Harry Potter And Half Blood Prince

Its official plot summary

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 defences 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, simmering 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. 

List of Harry Potter cast members

• Daniel Radcliffe as Harry Potter, who is now entering his sixth year at Hogwarts, with the Wizarding world at war.
• Rupert Grint as Ron Weasley, one of Harry's two best friends.He develops a relationship with Lavender Brown.
• Emma Watson as Hermione Granger, one of Harry's two best friends. Watson considered not returning for the sixth film,but eventually decided that "the pluses outweighed the minuses" and could not bear to see anyone else play Hermione.
• Michael Gambon as Albus Dumbledore. The legendary wizard and headmaster of Hogwarts. The revelation of Dumbledore's sexuality prompted Gambon to "camp up" around the set when off camera, but his on-screen performance is expected to remain unchanged from the previous films.
• Jim Broadbent as Horace Slughorn, the newly appointed Hogwarts Potions master. Broadbent described his costumes as "tweedy", and his character as "comic", while Radcliffe noted that "[Slughorn's] tragedy will outweigh the comedy".
• Alan Rickman as Severus Snape,the former Potions master, who finally achieves his goal of becoming Defence Against the Dark Arts teacher.
• Tom Felton as Draco Malfoy,a classmate of Harry, whom Harry suspects of carrying out a task for Voldemort across the year, and son of Narcissa Malfoy and nephew to Bellatrix. Unknown actor Tony Coburn will play Lucius Malfoy in a Hogwarts flashback.
• Bonnie Wright as Ginny Weasley,Ron's younger sister in her fifth year, for whom Harry develops intense romantic feelings. Her feelings for Harry never changed, and they finally become a couple near the end of the school year.
• Matthew Lewis as Neville Longbottom,a friend of Harry, Ron, Hermione and Ginny.
• Evanna Lynch as Luna Lovegood,^[2] a friend of Harry, Ron, Hermione and Ginny.
• Robbie Coltrane as Rubeus Hagrid, the Hogwarts gamekeeper and Care of Magical Creatures teacher.
• Maggie Smith as Minerva McGonagall,the Hogwarts Transfiguration teacher, deputy headmistress and head of Gryffindor.
• David Thewlis as Remus Lupin, a member of the Order of the Phoenix and former Defence Against the Dark Arts teacher.
• Natalia Tena as Nymphadora Tonks, a member of the Order of the Phoenix.
• Helen McCrory as Narcissa Malfoy, Draco's mother and younger sister of Bellatrix. McCrory was originally cast as Bellatrix Lestrange in Order of the Phoenix, but had to drop out due to pregnancy. Naomi Watts was previously reported as having accepted the role, only for it to be denied by her agency.
• Helena Bonham Carter as Bellatrix Lestrange, one of Voldemort's principal Death Eaters, older sister of Narcissa Malfoy, aunt to Draco, and cousin of Sirius Black.
• Timothy Spall as Peter Pettigrew, one of Voldemort's principal Death Eaters.
• Mark Williams and Julie Walters as Arthur and Molly Weasley,^[39][2] Ron and Ginny's parents.
• Jessie Cave as Lavender Brown,Ron's girlfriend. Watson described her as "perfect for the role," although Cave did not attend the open auditions.An open casting call was held for the part on 1 July 2007. Over 7,000 girls turned out for the audition and read from a scene with Madam Pomfrey, Hermione, and Ron. Yates tested Grint with the top five choices for Lavender, reading certain lines and kissing, to see which pairing had the best chemistry.