The missing Marauders
Mooney, Wormtail, Padfoot and Prongs (Remus Lupin, Peter Pettigrew, Sirius Black and James Potter's teenage animal alter egos who wreaked havoc around the halls of Hogwarts back in the day) featured prominently in the third Harry Potter tome, with tales of their exploits delighting readers and Harry himself alike.
By the time Prisoner of Azkaban made it to the big screen their backstory was seriously sliced, with no mention of the fact that Harry's dad was also an Animagus – able to transform into a stag at will – and no real explanation of how the marvellously insulting magical map of the castle they created came to be.
Mischief most definitely NOT managed: We solemnly swear that they were up to no good.
Pulling the plug on Peeves
Were you peeved about the omission of the pesky poltergeist?
Producers cast the dearly departed Rik Mayall as Hogwarts' most ghastly ghost, filmed his scenes and then cut them from Harry Potter and the Philosopher's Stone because they weren't entirely happy with how the character had been designed, apparently.
Peeves brought a sense of mischief and unbridled mayhem to the page. If you haven't read the books you've no idea what you're missing.
While the Triwizard Tournament dominated much of Harry Potter and The Goblet of Fire, a delightful subplot about a house elf called Winky showed us a new side to both Hogwarts and Hermione Granger.
Horrified at the thought that she was being served by house elves, Hermione Granger founded S.P.E.W – the Society for the Protection of Elven Welfare – and campaigned to have them paid.
When you consider the original reason she finally locked lips with Ron in Deathly Hallows – because he asked who'd save those same elves during the Battle of Hogwarts – you come to realise we've got plenty to be thankful to those little folk for.
Getting rid of the Gaunts
Voldemort's mother, grandfather Marvolo and uncle Morfin played a pretty pivotal role in the books, mainly as a result of being killed off. Merope (his mum) lived a pretty morbid existence in the Gaunt hovel, inspiring her to cast a spell on Tom Riddle Senior (his dad).
A rather unforgiving Voldemort later returned to their mud hut after murdering his muggle family, framed his uncle for the crime and saved a slice of his soul into a ring he stole from his mother's family. Here be horcruxes. They're important, right?
Never acknowledging the importance of Neville
Much is made of the fact that Matthew Lewis aged quite well, but his on-screen alias Neville Longbottom got a bit of a raw deal in the transition from the book.
In Order of The Phoenix we meet his mum and dad in St Mungo's Hospital and the tragic tale of their torture at the hands of the Death Eaters comes to light.
And then there's the fact that Neville could also have been the Boy Who Lived... Did you know that the prophecy about the one who could defeat the Dark Lord could have referred to him too?
James, Lily and Snape's love triangle uncharted
The ongoing saga between James Potter, Lily Evans and one Severus Snape was one love triangle too many for the Harry Potter films, apparently.
Readers delighted in discovering in Order of The Phonenix that Lily and 'Sev' had been proper pals, lamenting the end of their friendship when the future Potions master called her a mudblood...
The tale eventually resurfaced in Deathly Hallows Part 2 – when Snape revealed he'd been forever holding a torch for his flame-haired friend – but just think how marvellous it might have been if their teenage angst had been played out on screen.
Omitting the Other Minister
It's not often that we find the muggle world and magical community interacting but the opening chapter of Half Blood Prince was dedicated solely to it.
Outgoing Minister for Magic Cornelius Fudge brings Rufus Scrimgeour to 10 Downing Street, introducing his successor to the Prime Minister and informing him of Voldemort's return to power.
Fans can't quite decide whether John Major or Tony Blair would have been in power at the time, but it would have been rather enjoyable to see how the PM might have handled He Who Must Not Be Named.