Gozu

is a shinobi from Otogakure and a member of Team Guren.

Background
At some point in the past Gozu was dieing of thirst and food deprivation. Guren saved his life by giving him some water.

Personality
He is unsociable and quiet, making people unable to figure out what he is thinking, but his battle skills are without a doubt very dexterous. He relies on taijutsu and brute strength and preferred fighting alone. He holds a special sentiment towards Guren and was her most loyal subordinate, even stating "I will accompany you no matter where you go". The reason for this was that Guren saved his life while he was imprisoned by Orochimaru, giving him water when he was dying of thirst.

Abilities
He seemed to be quite strong since while his comrades were fighting in groups in the battle royal, he held his own by himself. The greatest example of his raw strength was shown from his ability to hold back the giant Three-Tails (albeit momentarily).

Nature Transformation
His body was altered by Orochimaru, giving him great physical strength and the ability to alter and turn his body into mud through Earth Release.

Utilising earth release he could shoot one or multiple shots of mud capable of trapping and slowing an opponent down or dig through the earth at high speeds by turning it into sand with chakra. He was also able to expand his body in a manner similar to the Akimichi clan's expansion techniques to enhance the strength of his arms or legs for more powerful strikes and accelerated movement. Gozu could also condense his form for even greater feats of speed.

Three-Tails Arc
After the selection battle Kabuto Yakushi and Guren held in the hideout, Gozu became Guren's subordinate. When Guren returns, she orders him and the rest of his team to dispose of Kakashi Hatake and Team 8.

As the arguably strongest member, he was sent in first to face off against Kakashi and draw him away. There, he quickly showed off his tremendous might that kept Kakashi on his toes. When Kakashi's cunning and skill proved too much for him, he pulled out his trump card to alter his body even further, giving him even greater speed and strength. In the end, he barely survived his fight against Kakashi, having sustained a broken arm and forced to retreat.

When he next appears, his arm healed, he watches as Guren faces Team 8. When her crystal barrier is destroyed, he is the first to charge in to Guren's aid. Later when Kabuto appears to retrieve Yūkimaru, Gozu joins them and is tasked with rowing the boat. Soon thanks to Guren and Yūkimaru's combined power, he finds himself in the presence of the Three-Tails. After Kabuto orders Guren to restrain the beast, Gozu goes to assist her without hesitation, allowing her to momentarily capture it. The Three-tails then creates a huge tidal wave which launches Gozu away from his team.

He manages to survive and wash up on shore with Rinji and the others. Immediately, his first thought is to find Guren and rushes off to find her. Later, he is seen fighting Sai, and is easily bound by his ink technique.

He senses Guren's chakra, and runs to save her from Kakashi. He is struck by Kakashi's Lightning Cutter and seemingly dies.

After Guren sacrifices herself to save Yūkimaru, Gozu is still shown to be alive in mud form at the bottom of the lake. The reason he admires Guren is because she was the only one to treat him nicely at Orochimaru's hideout and gave him water when he was dying. After Gozu and Guren get out of the lake, the two set off along with Yūkimaru.

Trivia

 * "Gozu" literally means "cow head".
 * Gozu was shown fighting Hinata in the fourth opening, but this never occured, as he fell to Kakashi before anything happened.