These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Complete Monster: Roxanne of Love and Hate, a former "Number One" of the Organization, differs from the majority of other villains in the series by being an outright cruel and violent sadist. Initially a low ranking warrior, Roxanne rose up the ranks by seducing/befriending and eventually murdering stronger warriors after stealing their techniques. Eventually, she set her sights on the existing Number One Cassandra, but when she saw Cassandra's technique, she decided it was unsightly and gave Cassandra the hated moniker "Dust-Eater." She later set up Cassandra's only friend to die a torturous death at the hands of a Awakened Being and mocked Cassandra by saying that her friend had looked as if she had "enjoyed" being played with by the monster, so interfering wouldn't have been right. Cassandra snapped and attacked her. Roxanne used the other 45 warriors as shields, relishing in their fear of Cassandra and cackling at how hideous Cassandra's abilities were. When Cassandra finally reached Roxanne, Roxanne gleefully impaled her head with the pommel of her sword, a technique stolen from her first victim.
Ending Fatigue: People are getting rather tired of the final fight with Priscilla, given how it amounts to countless resurrections and defeats taking turns with each other.
Ensemble Darkhorse: Teresa only had a few scenes, but quickly became very beloved by the fans.
Isley's a bit more of a literalexample, but his cool looks (both Awakened and human forms), awesome fighting style, and overall good treatment of Raki won him quite a lot of fans, especially after his sympathetic death and backstory.
Glurge: Through all of the hardships that Clare went through upon becoming a claymore, considered to be a failure and ridiculed because of so, she was able to press on because she always had Teresa with her... Very literally so since Clare was able to become a claymore by having the flesh from Teresa's decapitated head implanted in her.
God-Mode Sue: Priscilla. She's so incredibly powerful that no one can beat her, that even a piece of her arm is enough to possess Abyssal level Awakened Beings, and she hasn't lost a. Single. Battle. Gets quite annoying how the goal Clare had set for herself is unattainable with these odds.
Lets make it clear: she's making Madara fucking Uchiha have a harder time against opponents than Priscilla does. Priscilla even survives being cut up into tiny chunks! To clarify: while pretty much all of the characters have been sliced and diced in some way at one point or another, Priscilla's head is also sliced into tiny chunks. And somehow she manages to get to Cassandra's corpse, at least a good hundred feet or more away, and start chowing down. Despite having been in bite-sized pieces.What.
And she has NOTHING on Teresa, who is taking easy defeating her and gives Priscilla plenty of room for more power ups instead of killing her on the spot, because no matter what Priscilla does, Teresa is shown to be superior to her.
Perhaps an Ass Pull won't be needed after all, as Teresa coming back was hinted at earlier in the story — her presence inside of Clare was implied even as far back as Clare's first meeting with Miria, when Miria told Clare that Clare's rank bothered her because it had felt as if "the strongest was standing before [her]". Turns out that in a sense, it was true.
Roxanne's habit of Mega Manning the signature techniques of more powerful Claymores then killing her teachers was born of a twisted internal logic that makes putting her down pretty much mandatory, but watching an Awakened Being rape and torture a far weaker Claymore to death without lifting a finger to help moved her from the "Cut her head off now please." category to the "Will someone invent the wood chipper so she can be fed to it feet first?" category in the eyes of many readers.
Too Cool to Live: Teresa, Jean, Flora, possibly Ilena. Miria would have counted had she not been spared by the other Claymores. The author admitted that if Teresa had survived or were somehow revived, he would have to rewrite the whole story.
On the villain side, the original Abyssal Ones, and Chronos and Octavia, as of chapter 149. Yes, they would have had to die eventually but still...
Villain Sue: After many contenders, the true Villain Sue can only be, without a doubt, Priscilla.
The Woobie: By this point, it is easier to count the characters who are not Woobies on hand. The men of the organization, bandits, Roxanne, and most male Awakened Beings. Everyone else needs a hug, a glass of milk and a plate of cookies.
Cassandra, a Shrinking Violet who has, by chance, discovered a technique that she loathed but which propelled her to #1 of her generation. The only person who didn't loathe or fear her, the nameless #35, was killed in a disgusting, brutal, and completely senseless manner due to a certain Manipulative Bitch's machinations. Then, she was bloodily executed by her fellow Claymores. And on top of that, she was resurrected, brainwashed, sicked on her fellow warriors, and eventually awakened, tricked to fight Priscilla—only to be devoured by her just as the Ghosts seemed to have offed her for good.
Woobie Species: All the Claymores were orphans who were unwillingly put through painful and life threatening surgery so that they could fight man-eating monsters. Even the strongest ones don't get to live very long.