Son Gokū

The was sealed within an elderly man of unknown origin named Roushi who was eventually captured by Kisame Hoshigaki.

Background
It is currently unknown of what type of animal is the Four-Tails. The Four-Tails Jinchūriki was defeated by Kisame right after his introduction. According to Kisame, he had a difficult battle because he had to face many elemental fusions.

The Four-Tails was later extracted and sealed, leading to the old man's death.

Abilities
Little is known about the Four-Tails' abilities. The Four-Tails Jinchūriki has made use of its elemental fusion attacks, which is rarely seen outside of kekkei genkai. Roushi is able to fuse fire and earth elemental ninjutsu to create lava elemental ninjutsu.