Upon reflection, it's true that these individuals exist solely to make anime more dramatic and, not to mention, funnier.
1. The Cast of xxxHolic

xxxHolic revolves around Kimihiro Watanuki, a high school student plagued by his ability to see the supernatural, and Yūko Ichihara, a powerful witch who owns a wish-granting shop. When Watanuki requests Ichihara to rid him of his ability to see spirits, she agrees under the condition that he pays for his wish by working for her.
As one of Clamp's finest works, it's evident that xxxHolic's storyline is hard to criticize. However, some viewers find xxxHolic... challenging to watch due to its peculiar visuals. The elongated and slender character designs seem more suited for modern smartphones than traditional anime characters.
2. Haruyuki Arita - Accel World

Compared to the entire cast in Accel World, Arita Haruyuki is undeniably a short, overweight, and unattractive guy. Observing this character's face, there's no discernible highlight.
However, despite this unappealing appearance, he is incredibly intelligent and kind-hearted. Not only that, he possesses a unique ability to handle situations in the virtual world quickly. Nevertheless, placing Arita Haruyuki amidst beautiful heroines always leaves us feeling somewhat perplexed, almost like a bizarre joke.
3. The Cast of Aku no Hana

Aku no Hana has an incredibly enticing storyline, closely delving into the lives of these school kids whose existence is disrupted by mysterious forces primarily stemming from human psychology.
However, when adapted into anime, this work truly has issues. The characters' faces seem as if they are 'stuck' to the camera. This somewhat helps convey the characters' emotional states, yet it has a strong counter-effect in causing a significant drop in the viewer's mood.
4. Ryuk - Death Note

Ryuk, the Shinigami, clearly looks more like he stepped out of a Stephen King horror novel than something related to Death Note. Try comparing Pennywise the clown with Ryuk; both pairs complement each other much better than with Raito.
You may not know this, but Ryuk's current design is not Takeshi Obata's original concept. Initially, the mangaka envisioned the Shinigami to have a closer resemblance to Raito, with youthful black hair and even a pair of wings. However, such a design would have made Ryuk somewhat overshadow the intelligent yet flawed brainiac, leading to the creation of the current design.
5. Prison School

Prison School tells the tale of a girls' school recently admitting male students, with a unique group of five boys as the sole representatives amidst the alluring female student body.
In their early days at the school, our group of five boys gets caught peeping into the girls' bathroom. The consequence is that all five will have to endure life as prisoners in a makeshift prison built in the middle of the schoolyard. What's noteworthy is that all the prison wardens are stunningly beautiful, alluring, and possess extremely quirky personalities.
The most peculiar character among these five boys is undoubtedly Andre. His round face and peculiarly long ears make viewers unhesitant to nickname him Dumbo, after the long-eared elephant from the animated film. Upon reflection, it's quite fitting.