1. Bonnie Wright (plays Ginny Weasley)
For me, Bonnie Wright was not only a poor actress, but one of the few reasons I didn’t like the film series.. Her stiff performance, which may have passed as cute as a child just didn’t cut it when she reached adulthood. She is not only my least favorite Harry Potter actress, but also probably one of my least favorite actress of all time. It was unfortunate for her that she got a role that was so pivotal and major at such a young age when it is hard to tell how she would develop. If you think about it this way, she really was just unlucky and this whole thing was not her fault. Bottom line though: terrible performance.
2. Katie Leung (plays Cho Chang)
Leung's acting was very stiff and very boring. Daniel Radcliffe was probably like “Okay, I’m supposed to be really into her so I should look and act like it.” The problem was that it looked pretty one way and Leung wasn’t really returning "la passión". She played an important role and she didn’t do very well with it.
3. Stanislav Ianevski (plays Viktor Krum)
Ianevski had the look, the accent, but not the acting. Luckily his speaking was kept to a minimum. And what is that fist pumping in the opening Quidditch game? Never seen an athlete do that. And the dancing at the ball? He doesn’t look too into it. I feel like the director could tell Ianevski wasn’t all great and as a result took away some of Ianevski’s screen time.
4. Helena Bonham Carter (plays Bellatrix Lestrange)
“Helena Bohnham Carter is on this list? Are you for real?” You might say. Allow me to explain. You know when an actor is good, but they just go overboard with the character to the point it looks ridiculous? That is what happened here. The squealing, the fake tears, the hissing, the bellowing… I feel like Carter’s performance was one you either loved or hated. Personally, I hated it. She’s a well-decorated actress, and I liked her in The King’s Speech and Fight Club, but she just doesn’t really measure up here because her acting didn’t make sense.
5. Bill Nighy (plays Rufus Scrimgeour)
Nighy is a decently decorated actor. In Harry Potter, however, Nighy was really just overacting. The lip quivering? The exaggerated pauses? Overwhelming, but in a bad way. Luckily, Nighy doesn’t get a whole lot of screen time.
6. Robert Pattinson (plays Cedric Diggory)
Before becoming a Twilight star, the hunk known as R-Pats was cast as Cedric Diggory. Maybe Diggory’s character was to blame for him making this list. The character was set to be “infinitely fair minded and a fierce fierce friend” to quote Dumbledore. Doesn’t sound like a great set up for an interesting character to me. On top of that, Pattinson's performance was notably lackluster.
7. Clemence Poesy (plays Fleur Delacour)
She gets a small role in the fourth film and has an accent. She was supposed to be super pretty. Like nine out of ten pretty. But, to be honest, she really wasn’t. Additionally, her character just isn’t interesting at all. She has a nice good scream in the 3rd Triwizard Tournament event but that is about all she does.
8. Alfred Enoch (plays Dean Thomas)
Dean Thomas could have been a total badass. I mean, he shagged Ginny before Harry did. Harry had Dean’s leftovers. Dean could have been awesome. Unfortunately, his character was bland throughout the film. Part of this was Rowling’s fault. Given that he dated Ginny, Dean’s character was so undeveloped. He “fought” with Ginny in the sixth film/book? And they didn’t show it or talk about it? Enoch’s forgettable forgettable presence certainly didn’t help.