Anime characters can be assessed and evaluated in all sorts of ways, usually through their personalities and their actions. A person can also be evaluated based on their choice of clothing and accessories, which can say a lot about them. Some real and fictional people have rich and expressive wardrobes. Others, however, don't.
Some anime characters stick to the same outfit because it's literally the only outfit they have, or perhaps the character is so routine-oriented, it never occurred to them to try on other clothes. Or perhaps they wear a uniform and stick to that uniform out of duty or because they were never given other clothes.
10 L The Detective Just Needs Plain, Casual Clothes (Death Note)
The world's greatest detective, L, is known for many things, from his eccentric and focused personality to his mistrust of others and his reclusive ways. He is the very image of a "wild genius," and that reflects in his appearance, from his perpetual bedhead to the dark bags under his eyes.
His attire is another reflection of his eccentric ways. L could obtain any outfit he wanted, but he was only seen wearing white T-shirts and jeans, and only reluctantly will he wear shoes or socks. He feels no need to dress up; his actions and words are enough to impress others.
9 Ulquiorra Schiffer Only Needed His Arrancar Uniform (Bleach)
The cold, aloof villain Ulquiorra was an Arrancar in Sosuke Aizen's army, ranking #4 among the Espadas. He took great pride in this and made sure to wear a fancy white and black uniform to show his allegiance to Aizen. His uniform even comes with two long coattails that flap around as he walks.
Ulquiorra doesn't have access to other clothes, nor does he want any. His Arrancar uniform is all he wants, and he desires no other material possessions. When his uniform was damaged while fighting Ichigo, he simply swapped it out for a fresher version.
8 Benimaru Has A Cool Red Outfit (That Time I Got Reincarnated As A Slime)
Benimaru is an ogre swordsman and is utterly loyal to his boss, Rimuru Tempest the slime. His design and the designs of his fellow ogres are based on feudal Japan, from their ogre horns to their outfits and swords, and Benimaru takes his outfit seriously. It's a fancy ensemble, and Benimaru is only seen in that single outfit.
It's true that in Slime Diaries, Benimaru was seen in more casual clothes, but in the main story, Benimaru sticks to his default red outfit. He couldn't find a cooler set of clothes if he tried. It's his classic look, after all.
7 Rem Only Needs Her Maid Outfit (Re:Zero)
Rem is a horned ogre, like Benimaru, but she's not a sword fighter. Instead, Rem is primarily known for being a maid at the Mathers estate, loyally following Roswall's orders while also looking out for Subaru Natsuki, the hapless isekai hero of the hour.
Rem does have different clothes in flashbacks, but those scenes weren't part of the main events. She is also seen in sleepwear, but in all fairness, almost everyone has sleepwear. It can be safely said that this maid outfit is Rem's only notable outfit in the entire Re:Zero series.
6 Ectoplasm Always Wears His Iconic Trenchcoat (My Hero Academia)
Most characters in My Hero Academia have multiple outfits, since pro heroes and villains change into their costumes to fight and dress more normally when they're not fighting. Even All Might has multiple outfits, and Izuku has been seen in several different outfits. But not Ectoplasm.
Ectoplasm is only ever seen in his hero costume, including a beige trenchcoat with an enlarged, upright collar and a scary mask over his skull-like face. It's actually difficult to imagine him switching to ordinary clothes.
5 Lord Jiraiya Has Cool Clothes (Naruto)
Lord Jiraiya the toad sage is another anime character who did wear other outfits in flashbacks, but during the main events of the story, he wears the same outfit. Jiraiya has an outfit that loosely calls feudal Japan to mind, and that's some serious style.
Jiraiya wears this ensemble during everyday life and in combat alike, and he feels no need to don armor or even a helmet when facing foes such as Kisame Hoshigaki or the Six Paths of Pain. His outfit also includes a rather unique forehead protector; it's like a trademark of his.
4 Bruno Bucciarati Likes His White Suit (JoJo's Bizarre Adventure)
The Golden Wind story arc featured a handful of Italian Stand users and gangsters, one of whom was Bruno Bucciarati, wielder of Sticky Fingers. He was always seen in the same outfit, an eccentric white suit that contrasts with his dark hair.
Bruno's outfit loosely echoes Giorno Giovanna's own, with its form-fitting design and its open window at the chest. Bruno's outfit also features dark spots and several prominent gold zippers that reflect his zipper-based Stand.
3 Filo Likes Is Fond Of Her Blue Dress (The Rising Of The Shield Hero)
Filo was named after her race, the filolials, a species of birds that can morph into human forms. Filo is equally comfortable in both her avian form and human form, and Naofumi Iwatani made sure that Filo is well-dressed at all times. So, he had a custom outfit made for her.
In human form, Filo wears a blue outfit that boosts her charm even further, and she is quite fond of it. This is the only outfit Filo has or needs, and most importantly, this outfit morphs together with her when she changes into her large bird form. It would be costly to keep replacing her duds.
2 Tsukasa Shishio Only Wears Lion Pelts (Dr. Stone)
Tsukasa's clothes can barely even be called clothes at all, since his outfit is more appropriate for a Neanderthal. He fully embraces the new stone age, rejecting the laws, technology, and societal norms of the old era. He believes that it's time to start anew and only obey the laws of nature.
Accordingly, Tsukasa only wears lion pelts for clothes, and he didn't even bother making sandals out of leather or straw. He does, however, wear some basic red robes under the lion pelts. Even the Ishigami villagers have fancier outfits than this.
1 Tatsumaki Typically Wears Her Hero Costume (One-Punch Man)
The #2 superhero is the petite Tatsumaki, and she is nearly always seen wearing the same dark outfit, though she might also be seen in sleepwear once in a while. Tatsumaki feels no need to wear a flashy costume with a cape or helmet; her understated attire will do just fine, since her powers speak for themselves.
Tatsumaki's black dress has a prominent collar and is slit on both sides, showing most of her legs. She also has dark shoes. Her attire doesn't include any notable jewelry or accessories, though, in contrast to her little sister Fubuki, who does wear necklaces.