Well, there's a whole set of archetypes- if I had to break them down in HP, I'd break the main ones down since the rest are more of background... Not all of them will fit, mind you, but here is a basic run through:
Volger lists the most common and useful archetypes on page 36 of his book, "The Writer's Journey" as:
HERO: Someone who is willing to sacrifice his own needs on behalf of others.
MENTOR: A positive figure who aids or trains the hero. (Campbell called this the wise old man)
THRESHOLD GUARDIAN: Guardians at the threshold, placed there to keep the unworthy from entering.
HERALD: A new force that appears in Act One to bring a challenge to the hero.
SHAPESHIFTER: A person who changes constantly from the hero's point of view- often a love interest- someone who changes appearance, mood, and characteristic.
SHADOW: Usually the villain, antagonist, or enemy; one who is in conflict with the enemy, and is the energy of the dark side, the unexpressed, unrealized, or rejected aspects of something.
TRICKSTER: The embodiment of the energies of mischief and desire for change. Usually a comical sidekick, who serves the purpose of cutting the hero's ego down to size, and bringing him down to earth. They bring about healthy change and transformation.
Now, it's been a while since I've entered the HP world, and sadly enough, that series is one of the ones I have packed up at the moment, so I am only going to do a character/archetype analysis of the first book, since it's the one I know the best.
HERO: This (in all of the books) is Harry Potter of course.
MENTOR: Dumbledore/ Hermoine- I list Dumbledore as the "Old Wise Man" and Hermoine as the actual mentor since she usually knows what he doesn't- she's the smarts
THRESHOLD GUARDIAN: In the first book, this is the Uncle Vernon and Aunt Petunia, as they are blocking Harry from entering Hogwarts.
HERALD: This would be Hagrid, as he comes and takes Harry on the way to his new life- in effect, bringing the challenges of an entirely new world to him.
SHAPESHIFTER: I'm not really sure there is a shapeshifter in the first book. If I was forced to name one, I'd say that either Malfoy or Hermoine would be the closest in this- Ginny definately takes the cake for this role though, as she starts out a snot nosed little kid and then ends up his wife...
SHADOW: Lord Voldomort is the shadow present in the whole series; Malfoy is a little bit of a wanna be shadow, which is why I'd slot him as a shapeshifter and not shadow- he weeble wobbles on how devoted to the lord's cause he is.
TRICKSTER: Ron is the trickster; he's always messing up, being a dork, and bringing the comical relief in any moment- his bustedbutt wand is a prime example of this. His brothers, Fred and George are as well.
Mythologically, she borrows from every culture- the whomping tree reminds me of the dryad stories, the dragons are obvious, the trappings of the HP world are evidently from folklore, giant blood in is as well, ghosts are obvious as well, snake language is present in some epic I want to say- the point I am making is that none of the elements of HP are new. What she did was combined them in a way that was captivating. And if you look at the way the Hero's Journey is set up, she follows it almost exactly.
Volger has a reduced and simple layout of the Hero's Journey shown on page 18 that follows like this:
Call to Adventure
Refusal of the Call
Tests, Allies, Enemies
Approach to Innermost Cave
Reward (Seizing the Sword)
The Road Back
Return with the Elixir
If you look at these in the HP world, the books follow this layout. Bear with me, as again, I don't have my book available to me, so I am working from memory.
Ordinary World: This would be the "real world," aka the cupboard closet under the stairs.
Call to Adventure: The letters flying in the house.
Refusal of the Call: The Uncle and Aunt's burning/throwing away of the letters
Mentor: Dumbledore sends more letters and sends his messenger, Hagrid.
First Threshold: Diagon Alley trip
Tests, Allies, Enemies: The act of getting on the hogwarts express, sorting hat ordeal, potions class, flying a broom, three-headed dog encounter, troll encounter, etc.
Approach to Innermost Cave: three-headed dog, trap door.
Supreme Ordeal: Facing Quirrell and then Voldemort himself.
Reward (Seizing the Sword): Getting the Sorcerer's Stone from the mirror HP.
The Road Back: Harry passes out. (not much of a road back I know...)
Resurrection: Waking up in the school hospital.
Return with the Elixir: Going back home- a wizard.
Hope this helps guys.