There are many minor characters not included in the film, for obvious reasons, but there are a few key players also not included or their roles were reduced dramatically. I know I left out a lot but these were a few that had noticeable roles in the books. They were characters you remember and remember not appearing.
PEEVES
Peeves the Poltergeist is a Hogwarts ghost who wreaks havoc throughout the halls of the castle. Because this is the only answer anybody has when they discuss who was missing from the Potter films he’s top of the list. He was very close to making it into the film which may be why people are most annoyed. Or maybe it’s because he is a fun character in the books.
LUDO BAGMAN
In Goblet of Fire, Bagman plays a major role in both organising and announcing the Quidditch World Cup and the Triwizard Tournament. He’s a former professional Quidditch player and is the head of the Department of Magical Games and Sports at the Ministry of Magic.
RODOLPHUS LESTRANGE
Rodolphus is Bellatrix Lestrange’s husband who is imprisoned with her in Azkaban following Voldemort’s downfall. His omission meant we got more of Bellatrix’s creepy Voldemort love.
FRANK AND ALICE LONGBOTTOM
In both book and film we’re told that they were tortured by Death Eaters, but aside from one photo we don’t see them. The touching scene at St Mungo’s is omitted which is a shame because it’s wonderful.
AUGUSTA LONGBOTTOM (NEVILLE’S GRAN)
Augusta appears often in the later books, telling Neville how proud she is of him for being in the DA, she fights off an enemy Auror and puts him in St Mungos, goes on the run, and ends up fighting alongside Neville in the Battle of Hogwarts
WINKY
Winky is the Crouch family house elf who knew the family’s darkest secrets and yet was freed by Barty Crouch Sr. For supposedly stealing Harry’s wand during the Quidditch World Cup. Winky didn’t want to be freed and begrudgingly began working in the Hogwarts kitchen, drinking heavily while doing so. By extension all of the other house elves were left out as well.
PROFESSOR CUTHBERT BINNS
Professor Binns is the History of Magic professor at Hogwarts, who taught until a very old age and died in his sleep. Binns didn’t realise that he died when he woke up the next morning and continued to teach as a ghost.
MARVOLO, MEROPE, AND MORFIN GAUNT
The Gaunts are ancestors of Voldemort and distant descendants of the Peverells. In Half-Blood Prince, Marvolo is revealed as the grandfather of Tom Riddle who hates muggles and muggle-born wizards. Marvolo’s son Morfin is a Parseltongue and his daughter Merope falls in love with a muggle, Tom Riddle Sr., and places him under a love spell. The two have a son, Tom Marvolo Riddle aka Lord Voldemort. The Gaunt family plays an important part in Voldemort’s backstory in the books, but don’t appear in the movies.
THE PRIME MINISTER OF THE UNITED KINGDOM
The new muggle Prime Minister is visited by the Minister for Magic in Half-Blood Prince and introduced to the wizarding world.
ANDROMEDA AND TED TONKS
Nymphadora Tonks’s parents played a role in helping the Order of the Phoenix in the books, but they’re both cut out of the films.
Hogwarts Ghosts
BLOODY BARON, The Grey Lady, Nearly headless Nick, and Fat Frier
There was a severe lack of ghosts in the films. And it wasn’t just those four, I’m sure there were other ghosts mentions floating around. Yes we had Nick for a while but he didn’t exactly stick around past the second movie.
CHARLIE WEASLEY
Charlie is the second son of Arthur and Molly Weasley, and a member of the Order of the Phoenix, works with dragons in Romania.
ARIANA DUMBLEDORE
The full extent of Ariana’s story and her complicated relationship with her brothers wasn’t explored in the films at all.
CREEVEY BROTHERS
Both characters were condensed into Nigel in the film who still only appeared once, but the brothers were part of the DA and fought gallantly in the battle of Hogwarts. I honestly still picture them as brave twelve-year-olds, not like the older teens they would have been by the end of the books.
HEPZIBAH SMITH
Another character of Riddle’s past that provided more of his back story. She was a rich older witch who claimed to be the descendant of Helga Hufflepuff and was an avid collector of magical antiques. Riddle used Hepzibah to gain access to artefacts for his horcruxes.
MARIETTA EDGECOMBE
A Ravenclaw student and Cho Chang’s best friend, Marietta Edgecombe had a small but pivotal role in Order of the Phoenix . She signed up for Dumbledore’s Army but then rats Harry and his friends out to Umbridge (not Cho under the Veritaserum as the movie claimed). She gets SNEAK hexed onto her forehead which was irremovable.
EILEEN AND TOPBIA SNAPE (SNAPE’S PARENTS)
Their treatment of their son is another component of Snape’s overall personality problems. They were in an unhappy marriage and neglected their son. We could have had at least a quick scene of this in Snape’s memories but instead, we got more about Lily.
ERNIE MACMILLAN
Ernie was the Hufflepuff Prefect who supports Harry in his DA club and believes him about Voldemort’s return.
LEE JORDAN
Lee is a Gryffindor student two years above Harry. He is the Hogwarts Quidditch commentator and friend of Fred and George Weasley. So many of Fred and George’s hijinks were with Lee by their side. We got a quick look at him as the Quidditch commentator in the movies but that is all.
FIRENZE
A centaur who we first see in Philosopher’s Stone but his role as professor of Divinations is left out. Some of my favourite parts of Order of the Phoenix were his classes actually.
DEDALUS DIGGLE
Member of the Order of the Phoenix who took the Dursleys into hiding. In the films the Dursley’s leave in their car alone.
GRISELDA MARCHBANKS
Griselda was the Governor of the Wizarding Examinations Authority which ran the O.W.L, N.E.W.T., and W.O.M.B.A.T. exams Because so many school moments and exams were not included, there wasn’t much point in having Griselda in the films.
WILKY TWYCROSS
Wilky is the apparition instructor in Half-Blood Prince. Until I reread the book I completely forgot about him and the apparition lessons.
For a comprehensive list, here’s a list of all Harry Potter characters. And, it’s not all about who didn’t make the movies. Here’s a list of characters that didn’t even make it into the books!
Fantastic Beasts and Where to Find Them 
Dark times have come to Hogwarts. After the Dementors’ attack on his cousin Dudley, Harry Potter knows that Voldemort will stop at nothing to find him. There are many who deny the Dark Lord’s return, but Harry is not alone: a secret order gathers at Grimmauld Place to fight against the Dark forces. Harry must allow Professor Snape to teach him how to protect himself from Voldemort’s savage assaults on his mind. But they are growing stronger by the day and Harry is running out of time.
The summer holidays are dragging on and Harry Potter can’t wait for the start of the school year. It is his fourth year at Hogwarts School of Witchcraft and Wizardry and there are spells to be learnt and (unluckily) Potions and Divination lessons to be attended. But Harry can’t know that the atmosphere is darkening around him, and his worst enemy is preparing a fate that it seems will be inescapable.
Harry Potter’s third year at Hogwarts is full of new dangers. A convicted murderer, Sirius Black, has broken out of Azkaban prison, and it seems he’s after Harry. Now Hogwarts is being patrolled by the dementors, the Azkaban guards who are hunting Sirius. But Harry can’t imagine that Sirius or, for that matter, the evil Lord Voldemort could be more frightening than the dementors themselves, who have the terrible power to fill anyone they come across with aching loneliness and despair. Yet despite the relative safety of life at Hogwarts and the best efforts of the dementors, the threat of Sirius Black grows ever closer.
