Obviously, there are too many to count, but these are the ones I found particularly offensive or egregious.
Lily Evans - (inarticulate for seven books. rendered as a silent symbol of a dutiful wife and mother. reduced to being placed on a pedestal so Snape can have his precious tragic arc.)
Ginny Weasley - (entire recovery arc from being possessed left off-page, and more or less forgotten about until JKR brings her back to be a love interest. she deserved so much more.)
Dolores Umbridge - (is raped by centaurs in order to be taught a lesson. and this is laughed at.)
Petunia Evans - (is invariably blamed and badly treated, despite that Snape did similar things to her and somehow all is forgiven withhim.)
Sirius Black - (erasure of mental-health issues.)
Fleur Delacour - (demonized for being beautiful. borderline racist treatment.)
Cho Chang - (demonized for daring to sob about her boyfriend and defend her friend.)
Pansy Parkinson - (that whole damn article about “stupid girls” and JKR’s obsession with aligning Pansy with the girls that bullied her as a child.)
Bellatrix Black - (has to be killed by Molly to prove some point about motherly love being better than sexual love. isn’t given much characterisation beyond being a sadistic Bad Woman.)
Peter Pettigrew - (probably the biggest victim of JKR’s obsession with ~bravery~ and ~loyalty~ being the most admirable traits. essentially shunned throughout the entire series because of this. also another manifestation of Bad=Ugly.)
Lavender Brown - (demonised for being gossipy and giggly and liking boys and dating.)
Percy Weasley - (demonized for having ambition.)
(the rankings don’t matter that much beyond the first five, because I just found the treatments of Lily, Ginny, Umbridge, Petunia and Sirius to be the absolute worst. Not to say that the others aren’t awful, but those five really stood out.)
13. Slytherin House - because “those cunning folk use any means, to achieve their ends” clearly means “matters fuck all if you have a functioning brain, if a hat puts you in Slytherin when you’re eleven, you’re clearly gonna be the next Adolf Hitler”
