Shrieker/Anime Continuity

is a Togabito imprisoned in Hell. In his human life, he was originally an infamous serial killer until he died and became a Hollow. He was then defeated by Ichigo Kurosaki and sent to Hell.

Plot
Temporarily escaping from Hell, Shrieker attacks and devours several Shinigami in Karakura Town until he comes across Rukia Kuchiki, the object of his vendetta. He severely wounds Zennosuke Kurumadani and Rukia, but Renji Abarai's Bankai abilities prove too strong for him, and he is wounded by Rukia. As he falls to the ground, Shrieker opens up a portal and disappears back into Hell while promising to return and conclude his revenge. However, Gunjō later reveals that Shrieker's appearance in the Human World was an experiment he conducted, which he declares a success, and Shrieker was killed since he was no longer of use.

Powers and Abilities
High Spiritual Power: Since becoming a Togabito, Shrieker is stronger than he was as a Hollow, allowing him to catch an officer-level Shinigami off-guard.