Spoilers
Of the ones I actually remember...
• Colin Creevey- Harry fanboy from Chamber of Secrets, was petrified. Did nothing else until Deathly Hallows where he died offscreen
• Bartemius "Barty" Crouch Sr -Imprisoned his son for being a Death Eater
• Bartemius "Barty" Crouch Jr - Everyone thought he was Mad Eye in Goblet of Fire
• Amos Diggory- Cedric's father, literally did nothing else that I'm aware of.
• Marjorie Dursley- From the Dursley scene in one of the books ( want to say 3 or 4). Harry accidentally inflated her.
• Walden Macnair
• Olympe Maxime- Headmaster Half-Giant of Beauxbatons
• Cormac McLaggen- Tried to go out with Hermione in Half Blood Prince, she did for a little bit just to make Ron jealous
• Mrs Norris-Filch's cat
• Antioch Peverell- One of the original Deathly Hallow owners (I don't remember who had which)
• Cadmus Peverell- See Antioch
• Tom Riddle Sr- Obviously Voldemort's dad, still fairly unimportant
• Stan Shunpike- Worked on the Knight Bus, eventually imprisoned for being a Death Eater with little proof, but actually was one
• Hepzibah Smith
• Zacharias Smith
• The Fat Friar- Hufflepuff House ghost, but I don't think it did anything ever (just like Hufflepuff in general)
• Grawp- Hagrid's half-brother
• Great Aunt Muriel- I think this was the Weasley aunt who bashed Dumbledore at Bill and Fleur's wedding.
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