Hashirama Senju

, the, was the founder of Konoha, the older brother of the Second, and the grandfather of Tsunade, the Fifth Hokage of Konoha, and Nawaki. He is well known for his abilities to use the Wood Release, a Kekkei Genkai that combines Earth Release and Water Release, to create wood.

Background
Hashirama was originally the leader of the Senju Clan of the Forest. During the first wars he and the Senju clan constantly fought the Uchiha clan and he himself Madara Uchiha personally, even to the point that when someone hired the Senju clan, the opposing part would hire the Uchiha clan, and vice-versa. He and his clan offered a truce with the Uchiha Clan and allied with Madara, and the two of them, with their clans, founded Konohagakure.

Later on, Madara left the village because during the times of peace, he was called a monster by his clan, saying that he took his brother's eyes for his own selfish desires, when they were given to him freely in order to protect the clan. This conflict resulted in the battle between Madara and Hashirama at the Valley of the End, with Senju emerging as the victor. To commemorate the battle, two statues, of Madara and Hashirama, were carved into the earth around the waterfall. It is for this reason that Naruto Uzumaki and Sasuke Uchiha's fight at that location was noted to be ironic.

At some point he would gain control of several Tailed Beasts, that he would later spread out between the nations, as the peace talks were happening, and in order to equalize the powers between the nations. While he was Hokage, Hashirama defeated Kakuzu, who received orders from Takigakure to kill him.

However the war still waged on, and thinking about the future of Konoha, he and his younger brother, Tobirama Senju, the future Second Hokage, trained the young Hiruzen Sarutobi, the future Third Hokage. Long after founding Konoha, Hashirama died in battle, leaving behind his younger brother who inherited the Hashirama's title and thus became the Second Hokage.

Personality
He saw the people of Konoha as a part of his own family, and his legacy takes a firm root in the village. He was greatly respected by all and even Madara had respect for his strength. Hashirama appears as a kind and caring person, with a calm demeanour.

Konoha Invasion Arc
He and his brother are revived from the dead by Orochimaru using Impure World Resurrection to fight the Third Hokage during the invasion of Konoha arc. During this time he demonstrates his great Wood Release abilities and the same shows great Taijutsu skills. His soul is eventually sealed into the stomach of the Death God by the Third Hokage, along with his brother and Orochimaru's arms.

Yamato
It is revealed that Orochimaru had implanted Hashirama's DNA into sixty test subjects in an attempt to gain access to his Wood Release techniques and ability to control tailed beasts, producing Tenzou (later given the code name Yamato). However, he lost track of the test subjects and didn't realize that one had survived.

Abilities
Hashirama has been noted by both Madara Uchiha and several Konoha Jonin to be regarded as the most feared ninja of his time. He was said to be one of or perhaps the most powerful of ninjas during the ninja wars, and the only person who was capable of matching him and his clan was Madara and his Uchiha clan. Even so, he was undoubtedly an extremely formidable ninja, defeating both Madara and the Nine-Tailed Demon Fox (who was under Madara's control at the time). This is remarkable since Madara is a wielder of the Eternal Mangekyo Sharingan, an advanced form of the mangekyo sharingan. Defeating the demon fox alone would be a legendary feat, as the Fourth Hokage has to actually give up his life to seal the demon fox. He also defeated the powerful Akatsuki member Kakuzu at some point. During his resurrected corpses battle with Hiruzen he is shown to be a considerable hand to hand combatant and could use powerful Genjutsu. Flashbacks to his battle with Madara show he also had some summoning prowess, conjuring various weapons via scrolls.

He was most famous for his Wood Release jutsu, an ability to mix earth and water natured chakra to create a new element: wood. By converting chakra into source of life, he was able to create trees and cause them to grow to great sizes and diverse shapes at will. This ability was apparently unique to him, since his granddaughter Tsunade did not inherit this talent, and Yamato only acquired it through genetic manipulation by Orochimaru. Yamato has also shown great skill in standard water and earth techniques so it is presumed Hashirama could as well.

The ability Orochimaru most highly praised him for however was his unique ability to control the Tailed Beasts bending them to his own will, and suppressing their chakra. Madara also mentions that at one time he had several tailed beast under his control and later dealt them out to the other great Hidden villages in order to equalize the balance of power. It would seem this ability is greatly amplified by his very valuable necklace composed of a shard of crystalline chakra, though how this works is unknown.

Trivia

 * The Necklace worn by Tsunade and later worn by Naruto originally belonged to Hashirama.
 * "Senju" (千手) means "A Thousand Hands", making a metaphoric association with trees and his ability Wood Release.

Quotes

 * "Being Hokage means believing in your people just as much..., as they believe in you."
 * "Whenever you live, there's always war."