Half Blood Prince - Debunked Rumours

HBP will not contain the chapters: 'Lupin’s Papers', 'Pettigrew’s Pamphlets', 'Sirius’s Circulars' or 'the Pocket Crosswords of Severus Snape'.
Colin and Dennis Creevey won't be the new Gryffindor Beaters - the beaters will be totally new finds of the captain's.
Nicolas Flamel will not teach Potions at Hogwarts, as when he destroyed the Philosopher's Stone, he died.
Harry Potter will not be the new Minister of Magic
Luna and Neville will not get together in HBP.
Half-Blood Prince will not be 38 chapters long.
Harry will not stand trial again in HBP, he leaves the Dursleys early for a "much pleasanter" reason than a court case.
There will be no character named "Icicle," and JK said that she didn't recall saying there ever would be.
Dumbledore is not related to Harry
Harry is not related to Voldemort who is not related to Salazar Slytherin.
Lily Potter is definately 100% dead.
Lily was not a death eater either!
No prequel books are planned (no books before Harry's time at Hogwarts)
Crookshanks is not an Animagus
Neville is not the son of Peter Pettigrew
Remus Lupin does not have a twin brother.
The next book will not be called "Harry Potter and the Green Flame Torch" or "Harry Potter and the Mountain of Fantasy"
JK does not have any parts in the films

Debunked Book Titles

These are book titles which circulated as possibilities. All have since been declared rediculous, specially since the official release of the title 'Deathly Hallows'.