Fishbone D

is Hollow who attacks the Kurosaki Clinic on the night Ichigo meets Rukia. He is subsequently purified by Ichigo after the latter receives Rukia's Shinigami powers.

Appearance
He is a Humanoid Hollow, approximately 16ft in height, with a fish like mask and a dorsal fin on his back. His shoulders are plated with what appears to be a part of his mask and his body is covered with dark gray stripes, resembling the scales of a fish.

Trivia

 * Like other Hollows he was left unnamed in the manga and only had his name revealed in the Book of Souls databook.