Bleach is a beloved anime/manga franchise with an ensemble cast of characters, from Soul Reapers to humans to the Arrancars and more. Ichigo Kurosaki is the hero, and he is soon joined by his friends, from Yasutora "Chad" Sado to Uryu Ishida and Rukia Kuchiki. Many other characters appear too, but not all of them stick around.
It's true that in a broad series like this one, not every character can be the star. Still, there are some Bleach characters who were either killed in their first battle, or had one or two major scenes before becoming little more than bystanders (or they just had a token appearance much later and nothing ore). Which characters didn't get their due?
10 Momo Hinamori, Squad 5 Lieutenant
Momo Hinamori is a high-ranking Soul Reaper, and for a time, she served under Captain Sosuke Aizen until he outed himself as a traitor. Poor Momo was misled and used, and she ended up fighting her fellows out of misplaced grief. Later, she sorted through these feelings.
Momo did appear again in the Thousand-Year Blood War arc, but she didn't do much aside from some token healing, and she largely watched as her new Captain Shinji Hirako and other heroes did the heavy lifting.
9 Don Kanonji, The Cable Star
Don Kanonji is an eccentric and flamboyant fellow who is the star of his own TV show, making use of his meager but authentic gifts with spirits to thrill audiences across Japan. He can see Pluses and Hollows, but his spirit powers are too weak to actually do any fighting.
While Ichigo couldn't possibly ask Don to fight with him against powerhouse foes like Grimmjow Jeagerjaques, Don could have made a few more cameos, or even invited Ichigo to his show at some point. He's simply too funny to get rid of.
8 Soken Ishida, The Beloved Quincy Expert
Soken Ishida was already deceased even when Season 1 started, so he appeared in flashbacks instead. Soken was Uryu's grandfather, and it was he who taught Uryu the ways of the Quincy tribe. He was a very important and beloved member of the family, at least to Uryu.
Soken appeared a few times in Uryu's flashbacks, mostly in terms of how he trained Uryu to use certain Quincy techniques. Later, when Uryu joined the Wandenreich, the story could have shown a few more touching Soken flashbacks, or at least mentioned him once or twice.
7 Izuru Kira, Squad 3 Lieutenant
Izuru Kira is the second-in-command of Squad 3, once serving right under Captain Gin Ichimaru (now Rojuro Otoribashi). Izuru is serious and grim, and his zanpakuto, Wabisuke, embodies the idea of apologizing for causing mayhem and destruction.
During the final story arc, Izuru was swiftly cut down by the Sternritters before he could do anything, and later, he had at most one forgettable fight against the Sternritter. It's a shame, since his shikai and battle creed are both so interesting.
6 Jidanbo, The Gate Guardian
Jidanbo is one of the gate guardians in the Soul Society, and he was one of Ichigo's first-ever opponents during the Soul Society arc. He is a tough but ultimately kind fellow who simply takes his job very seriously. He just wants to impress his bosses, after all.
Jidanbo did pretty much nothing else once Ichigo defeated him and destroyed his beloved cleavers, and he made a token second appearance when the Captains and Lieutenants surrounded Sosuke Aizen. Otherwise, Jidanbo was finished as a character.
5 Aaroniero Arurruerie, The Hungry Espada
The two-headed Espada named Aaroniero Arurruerie is an odd one by any standards. He is a Gillian Arrancar who has eaten 33,650 Hollows and absorbed all their spirit energy and abilities, making him a one-man army. He also obtained Kaien Shiba's body and through it, the zanpakuto called Nejibana.
Aaroniero made clever use of Kaien's memories to put psychological pressure on Rukia, but that was his one and only battle before getting killed, and he didn't really use his army-body's full abilities before Rukia killed him. Now, fans can only wonder what could have been.
4 Tier Halibel, The Shark Espada
Tier Halibel was once the #3 Espada, and she was like a tough big sister figure for her three fracciones. She is merciless to the Soul Reapers but is otherwise fair, and not at all bloodthirsty. She was cut down, but not killed, when Sosuke Aizen decided to not make use of her anymore.
Halibel clashed with Yhwach off-screen and lost to him, and was last seen chained up inside Silbern, the Quincy fortress. If only Ichigo and his friends broke her out, so she could help them take down the Quincy army. That would have been interesting to see, but instead, she simply vanished from the story.
3 Captain Rojuro Otoribashi, The Frilly Soul Reaper
Rojuro "Rose" Otoribashi is one of the Visoreds, and he is often seen with Kensei Muguruma. Rojuro is noted for his stylish gentlemanly clothes and personal flair, but he doesn't often get a chance to prove himself. His performance in the Fake Karakura Town is forgettable, and things get worse from there.
In the final arc, Rojuro is treated as cannon fodder by the narrative, and he is written out has a "meh" Captain who met his match against the Sternritter. Poor Rojuro simply faded out of the story and never made a real impact on anything.
2 Sora Inoue, The Big Brother
Sora Inoue was the big brother of Orihime Inoue, and he felt deeply responsible for her when their parents abandoned them. Sora died, however, and he came back as a minor Hollow named Acidwire. Ichigo faced him, and purified his soul at last.
Sora never appeared again after that, and he was mentioned very few times after that. Given how important he was to Orihime, he could have appeared in a few more flashbacks or at least mentioned in conversation, but it was not to be. He was soon gone.
1 Karin & Yuzu Kurosaki
Karin and Yuzu Kurosaki have a similar role in the story and usually appear together, so they may be counted together. Once in a while, these sisters do appear in the story, but only as bystanders, or to act as a foil to Ichigo's supernatural life wih their decidedly mundane interests. Nothing wrong with that.
However, these sisters still could have had a bigger role in the lore, and perhaps they could have even learned about their mixed Soul Reaper and Quincy heritage. But before long, they were making cameo appearances at best, and the story simply didn't find room for them. It seems there was only room for one Kurosaki.