Title: Harry Potter and the Half-Blood Prince (film)
Content:  Mark Williams plays Molly’s husband, Arthur, a member of the Order of the Phoenix while Natalia Tena plays fellow member, Nymphodora Tonks. Bonnie Wright and James and Oliver Phelps play Ron’s siblings, Ginny, Fred and George while Devon Murray, Alfred Enoch and Matthew Lewis play Gryffindor students, Seamus Finnigan, Dean Thomas and Neville Longbottom while Evanna Lynch and Katie Leung plays Ravenclaw students, Luna Lovegood and Cho Chang. Jamie Waylett and Joshua Herdman play Slytherin students, Vincent Crabbe and Gregory Goyle. Helen McCrory plays Narcissa Malfoy, Draco’s mother and Bellatrix’s sister and David Legeno plays werewolf, Fenrir Greyback. Jessie Cave, Anna Shaffer and Freddie Stroma play Gryffindor students, Lavender Brown, Romilda Vane and Cormac McLaggen while Rob Knox plays Ravenclaw, Marcus Belby.
Title: Harry Potter and the Half-Blood Prince (film)
Content: Daniel Radcliffe as Harry Potter: A 16-year-old British wizard who now enters his sixth year at Hogwarts School of Witchcraft and Wizardry. ; Rupert Grint as Ron Weasley: One of Harry's two best friends. ; Emma Watson as Hermione Granger: One of Harry's two best friends. ; Helena Bonham Carter as Bellatrix Lestrange: One of Voldemort's principal Death Eaters and Draco Malfoy's aunt. ; Jim Broadbent as Horace Slughorn: The newly appointed Potions master who held the position before. ; Robbie Coltrane as Rubeus Hagrid: The Hogwarts gamekeeper and Care of Magical Creatures teacher at Hogwarts. ; Warwick Davis as Filius Flitwick: The Charms master and head of Ravenclaw. ; Tom Felton as Draco Malfoy: Harry's rival and recipient of Voldemort's secret mission. 
Title: Harry Potter and the Half-Blood Prince (film)
Content:  Michael Gambon as Albus Dumbledore: The headmaster of Hogwarts. ; Alan Rickman as Severus Snape: The former Potions master, current Defence Against the Dark Arts teacher and head of Slytherin. ; Maggie Smith as Minerva McGonagall: The Hogwarts Transfiguration teacher, deputy headmistress and head of Gryffindor. ; Timothy Spall as Peter Pettigrew: The Death Eater who betrayed Harry's parents to Voldemort. Pettigrew has no lines in this film, but appears as a servant at Snape's house. ; David Thewlis as Remus Lupin: A member of the Order of the Phoenix and Harry's ex-Defence Against the Dark Arts teacher. ; Julie Walters as Molly Weasley: The Weasley matriarch and a mother figure to Harry.  Gemma Jones returns to the cast as Hogwarts’ matron, Poppy 
Title: Harry Potter and the Half-Blood Prince (film)
Content:  Harry Potter and the Half-Blood Prince is a 2009 fantasy film directed by David Yates and distributed by Warner Bros. Pictures. It is based on J. K. Rowling's 2005 novel of the same name. The film, which is the sixth instalment in the Harry Potter film series, was written by Steve Kloves and produced by David Heyman and David Barron. It stars Daniel Radcliffe as Harry Potter, alongside Rupert Grint and Emma Watson as Harry's best friends Ron Weasley and Hermione Granger. 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. The film is the sequel 
Title: Harry Potter (character)
Content:  Potions, using an old textbook once belonging to a talented student known only as "The Half-Blood Prince." The book contains many handwritten notes, revisions, and new spells; Hermione, however, believes Harry's use of it is cheating. Through private meetings with Dumbledore, Harry learns about Voldemort's orphaned youth, his rise to power, and how he splintered his soul into Horcruxes to achieve immortality. Two Horcruxes have been destroyed—the diary and a ring; and Harry and Dumbledore locate another, although it is a fake. When Death Eaters invade Hogwarts, Snape kills Dumbledore. As Snape escapes, he proclaims that he is the Half-Blood Prince (being the son of a muggle father and the pure-blood Eileen Prince). It now falls upon Harry to find and destroy Voldemort's remaining Horcruxes and to avenge 
Title: Harry Potter and the Half-Blood Prince (film)
Content:  Christian Coulson, who played the young Tom Riddle in Chamber of Secrets, expressed an interest in returning in the role for flashback sequences; Yates responded that Coulson was too old, nearing 30, to be playing the role. Jamie Campbell Bower, who appeared in Sweeney Todd: The Demon Barber of Fleet Street, previously noted that he had his "fingers crossed" he would be cast as a young Riddle. (Bower was, however, later cast as the teenage Gellert Grindelwald in Harry Potter and the Deathly Hallows – Part 1.) Thomas James Longley was the original choice to take on the role but Riddle was ultimately played by Hero Fiennes-Tiffin as a child and Frank Dillane as a teenager. Helen McCrory 
Title: Harry Potter and the Half-Blood Prince (film)
Content:  as Narcissa Malfoy, Draco's mother and younger sister of Bellatrix. McCrory was originally cast as Bellatrix 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. Both Clémence Poésy and Chris Rankin, who had played Fleur Delacour and Percy Weasley respectively, were interested in returning, but did not appear in the film. After Bill Nighy expressed an interest in appearing, Yates confirmed that Nighy would be his first choice for the role of Minister for Magic Rufus Scrimgeour. Scrimgeour's character was ultimately cut from the film, but Nighy appeared in his role in Deathly Hallows.
Title: Harry Potter and the Half-Blood Prince (video game)
Content:  Several members of the Harry Potter film series lent their voices (some for the first time) to their characters in game. Among these, Rupert Grint played Ron Weasley, Bonnie Wright played Ginny Weasley, Warwick Davis played Professor Flitwick, and Tom Felton played Draco Malfoy.
Title: Fictional universe of Harry Potter
Content:  "Half-blood" is the term applied to wizards and witches who have magical and Muggle ancestors in their family trees. They are the most common blood status, far outnumbering pure-bloods and Muggle-borns. Rowling has stated that, of the Hogwarts annual intake, fifty per cent are half-bloods. Pure-blood supremacists view half-bloods as inferior to them, although superior to Muggles and Muggle-borns. The Malfoy family, a family of wealthy wizards who showed disdain to Muggles, attempted to maintain blood purity but found it acceptable to marry half-bloods if there was a dearth of marriageable pure-bloods. Voldemort is a half-blood, and his most guarded secret which few wizards know is that his father was Tom Riddle, a Muggle. Severus Snape is also a half-blood (he gave himself the nickname "The Half-Blood Prince"), as his father Tobias Snape was a Muggle. Harry himself is a half-blood, since his pure-blood father, James, married a Muggle-born witch named Lily, and his maternal grandparents were Muggles.
Title: Hero Fiennes Tiffin
Content:  Prior to his acting career, Fiennes Tiffin worked jobs as a landscaper and caterer. He made his first film appearance as Spartak in the 2008 drama film Bigga Than Ben. He got the part of Tom Riddle (the young Voldemort) in Harry Potter and the Half-Blood Prince from thousands of young actors who auditioned for the role, though at least one publication alleged that his family connections alone landed him the part. Director David Yates said he was cast due to his ability to find "the darker space" in his line readings, and that he did not get the role due to his relation to Ralph Fiennes, his uncle who plays Voldemort, but admitted the family 

Question: who plays young voldemort in the half blood prince?
Answer: Hero Beauregard Fiennes-Tiffin.