Voldemort's first appearance
After a slightly naff glimpse of a cloaked you-know-who when we're finding out about Harry's mum's backstory, the showdown at the end of The Philosopher's Stone gave us an unexpected glimpse of the big bad.
When Professor Quirrell removes his turban to reveal that the essence of Voldemort is living on the back of his head, the series also announces its intention to join the subgenre of family films that are actually pretty darn scary. Shame his achilles heel is being touched by Harry. At least the series learned how to craft more impressive battles in the following episodes.
Dementor on the tracks
Alfonso Cuaron directed Azkaban (his first and only Potter movie), and brought some credibility (and yes, darkness) to the franchise that many had written off as kids' stuff. This is the moment when the Hogwarts Express, ferrying the students to the start of a new term, is stopped dead by the arrival of the Dementors, Azkaban's prison guards.
Chilling (literally, the windows freeze up), the sequence conjures up and sustains a potentially bed-wetting amount of fear, as the caped spectres slowly edge their way into the carriages. The scene ends with a neat introduction to new Defence Against the Dark Arts teacher Remus Lupin.
If Azkaban remains a high-point in the franchise, this scene is possibly the high-point of the film.
Meet Lucius Malfoy
Such is Jason Isaacs' presence in the Potter movies that it's surprising to find out how little screentime he actually gets throughout the series. He makes his first appearance in the second movie, alongside his delightfully odious son Draco.
Isaacs can do hissable villainy in his sleep, and this otherworld Nazi is one of his best. He even manages to ooze evil charisma from underneath a truly awful wig. From this point on, you know that any time he's going to be on screen will be an absolute pleasure.
We know that Ron Weasley knows his way around a chessboard, as we've seen him taking on Harry on a nifty little magic board earlier on in the movie. As the three moppets head towards their first climactic showdown of the series, they pass some underwhelming obstacles (Fluffy for example), but the supersized chess game is an impressive set piece.
The lumbering pieces come to life as the kids take part in the match, with the kind of scale and tangibility that brings the best Harry Potter magic moments to life.
Arguably, this is the moment that audiences had been waiting for since the start of the trilogy. Undoubtedly Harry's biggest challenge, he faces off against the reincarnated form of his ultimate nemesis.
And the first appearance of Voldemort 'proper' doesn't disappoint, with Ralph Fiennes able to emanate serious amounts of menace from far beneath some extremely impressive make-up work. The reveal of the big bad was worth waiting for.
The story begins
Dumbledore, McGonagall and Hagrid get together to drop off baby Harry at his surrogate muggle home. John Williams' magical music bars, that will be synonymous with the series for the next decade, set the exciting tone, as does the presence of the fantasy figures in the everyday avenue.
Throw in Dumbedore's tinkering with the streetlights, McGonagall's feline transformation and Hagrid's arrival by flying motorcycle, and the fantasy franchise clearly and proudly marks its arrival…
Order of the Phoenix may not have had the sheer number of set-pieces gifted to the earlier franchise entries, but it more than makes up for it with a jaw-dropping blowout of an ending.
First Dumbledore's young army fly across an illuminated, nighttime London to save Sirius from torture in the Department of Mystery. There they have to take on Voldemort's Death Eaters, including new-addition-to-the-franchise Helena Bonham Carter as Bellatrix Lestrange.
As well as all of these talented magic people facing off against each other in the prophecy room, the piece de resistance is the showdown between Dumbledore and Voldemort, both at the height of their powers.
Getting lost in the maze
Bookending the Voldemort showdown is the final Tri-Wizard task, as the four competitors seek out the cup from within a threatening, labyrinthine maze. If the oppressively high hedges and angry vines don't get to you, the maze still might mess with your head, and there's your fellow competitors to worry about.
The true highlight moment has to be a brave move from director Mike Newell though: when Harry transports back with the cup and Cedric's lifeless body, the crowds initially cheer, thinking a happy winner has returned, but slowly the grave realisation of what has actually happened sinks in, as the crowd goes quiet…
Snape's first lesson
Up to this point, you've only glimpsed Snape sitting at the head table in the Great Hall. When he takes his first lesson, audiences got their first proper taste of more Rickman magic in action.
There's the slow, measured, sinister cadence. The refusal to back down when it comes to tormenting star pupil Potter. The delicately balanced ambiguity that'll remain a highlight of the entire series. Another classic Rickman villain (or is he?) to sit alongside Hans Gruber and the Sheriff of Nottingham in his superlative rogues' gallery.
Having managed to drink the liquid, collect the locket and apparate back to Hogwarts, Dumbledore is put in an awkward position when Draco Malfoy (fulfilling his 'unbreakable' vow) holds him at point blank wand range.
The real kicker is when Malfoy loses his bottle and fails to complete the task, and Severus Snape steps up to do the deed. Dumbledore gets his Gandalf moment, and there's an emotional send-off when the students hold a wand-light vigil around his fallen body.
A sombre close to the movie, leaving everyone eagerly anticipating the final installment with uncontrollable fervour.