Hopefully, everyone had a happy merry Christmas. Even with all the absolute chaos happening outside.
Bleach is an anime/manga Shonen series following Soul Reapers/Shinigami, people who gather human souls that have since moved on from the living world and ascend them to the afterlife/Soul Society. These souls that have remained on Earth soil have a variety of reasons why for they chose not to ascend, but if they aren't ascended in time, these souls morph into paranormal beasts called Hollows. They feed off the souls of still-living organisms, particularly humans. While they are all in some way violent and bloodthirsty, the majority of Hollows fall into Gray Zone amorality since they are only driven by their desire to consume souls. However, some of them are capable of remembering their past lives and take grudges out for the ones responsible for their deaths. Case in point, Shrieker.
Who is Shrieker
What's known about Shrieker's human life is that he was an infamous serial killer who took sadistic pleasure in watching his victims' faces of anguish as he stabbed them to death. His victim count was around eight. His most recent victim was the mother of Yuichi Shibata, stabbing her numerous times while she protected her son. Following them onto the balcony, after finishing off Yuichi's mother, Yuichi grabbed him by the shoelaces, causing him to trip and fall from the balcony twenty stories to his death.
When he was reborn as Shrieker, the killer returned for vengeance against Yuichi and ripped his soul from his body. But instead of eating Yuichi's soul straight away, Shrieker decided to "play" a game with Yuichi and placed his soul within a cockatiel. The wicked Hollow offered him a challenge that if Yuichi could avoid him for three months, Shrieker will bring his mother back to life (obviously he couldn't since nobody has that ability). For the next few months, Yuichi ran from Shrieker, who killed and feasted on the souls of everyone who came in the possession of the cockatiel. He was also responsible for killing two Soul Reapers who attempted to free Yuichi by forcing his soul to ascend to the Soul Society.
Yuichi as a cockatiel eventually comes into possession of Yasutora Sado, a large student at Karakura High School and friend of main protagonist Ichigo Kurosaki. Shrieker eventually finds them and attempts to kill them by dropping a steel beam on them, but Sado blocks it. When that fails, Shrieker causes a large traffic accident. Sado and Yuichi get away, but Sado is scarred in the back by a large hand-shaped burn. Ichigo and Rukia come aware that it was a Hollow involved and Ichigo's sister Karin falls ill from the effects of the Hollow nearby. Rukia has Sado escort Yuichi away and Ichigo escorts Karin away while she fought Shrieker head-on. Due to limiting her powers to that of an average human, Rukia was quickly bested by Shrieker, who sadistically informed her of the Soul Reapers he ate. Before he could eat her as well, Sado arrives. Despite not being able to see Shrieker, Sado could feel his presence, and with his brawns and Rukia's brains, they manage to overwhelm him. However, Shrieker has the last laugh by releasing multiple leaches that explode when they resonate with a sonic boom, seriously wounding them.
Fortunately, Ichigo arrives in time to continue the battle for his friends. He manages to avoid the leach bombs and multiple frog-like monsters before getting his sword at Shrieker's neck. He forces Shrieker to explain his history about Yuichi and what he did to his mother, which Shrieker delightfully does so. Before Ichigo could finish him off, Shrieker managed to throw more frog monsters at Ichigo and was about to unleash another sonic boom. But Ichigo punches his hand into Shrieker's mouth holding multiple of the leaches, making him unable to detonate them without blowing himself up. Having tricked the Hollow, Ichigo rips out Shrieker's tongue before slicing his mask in half, defeating his Hollow form. Unlike all of the other Hollows Ichigo previously defeated, Shrieker committed horrific crimes in his past life and was no soul worth refuging. As such, the gates of Hell appear and drag Shrieker inside to forever atone for his sins. Rukia peacefully ascends Yuichi to the Soul Society to be with his mother and all seems fair and square...
Except that wouldn't be the last to be seen of Shrieker, as he managed to return as a Togabito (damned souls) in a special episode to promote the fourth film Bleach: The Hell Verse. He devours numerous Soul Reapers in Karakuna Town before attacking Rukia out of vengeance for his previous defeat, managing to overwhelm her and Zennosuke Kurumadami due to new stronger powers such as extreme agility and firing out his explosive leaches through wrappings in his arms. But with assistance from Renji Abarai's Bankai abilities, Rukia manages to defeat him. A portal to Hell appears below Shrieker and drags him in, but he swears to keep coming back until his revenge is completed. However, this was only an experiment by Gunjō as a test for stronger Togabito to escape from Hell. And since the experiment was complete, Shrieker served his use and his soul was permanently silenced. So yeah, he isn't coming back.
None. He's a sadistic killer both as a human and Hollow, taking full pleasure in watching his victims die. While he offered to bring Yuichi's mother back to life if he could avoid becoming Hollow lunch for three months, he was only bluffing about an ability he doesn't have just to bring tasty souls to him as he chased after the soul of a young boy trapped in a weak cockatiel body that he psychologically tortured. First by killing his mother in front of him, and then all of the innocent civilians who came in his possession.
As far as the Hollows go in the series, it's Shrieker who stands out as the meanest and vilest of the bunch. As bad as the majority go with the number of innocent humans they devour to obtain their souls, the Zanpakuto can cleanse the souls of their sins WHILE they were Hollow. Shrieker was a monster in his life as a serial killer while the rest were normal citizens. Worse, he is the only Hollow in the series to meet the fate where he was not cleansed but rather damned to Hell, which says a lot about how bad he was. Even the evilest Hollows fought by Ichigo and Rukia such as Grand Fisher who toys with his prey through psychological torture and Metastacia who killed Kaien Shiba and boasted about it to his squadron, they were able to be cleansed and ascended to the Soul Society.
There are other heartless assholes in this series like Yhwach, Sōsuke Aizen, and Szayel Aporro Granz. In a way, they attribute more to the standards given they have far more screen time than Shrieker, but their human/Soul Reaper resources are different in powers than the Shrieker Hollow and affect the story differently.
I say yes but the outcome is decided by you.