A Ninja who has achieved the name of Kage (Shadow), the strongest ninja of a Hidden Village, the Third Hokage was the leader of Konohagakure. Mostly referred to as the Third because he was the third of five Konoha ninja to gain the title Hokage; his face was also the third face on the monument carved on the mountain overlooking Konoha Village. In the beginning of the manga and anime, he and Umino Iruka were virtually the only people in Konoha Village to have any sympathy or liking for Naruto.
Future Legends: A younger Sarutobi before he became Hokage with his students- the young Tsunade, Orochimaru and Jiraiya.
Said to be the strongest among all the Kage, he was called The Professor (プロフェッサー, Purofessā) or even God of Shinobi (忍の神, Shinobi no Kami) because of his genius. He had a large and impressive arsenal of jutsu, which he had learned over his many years serving Konohagakure. In fact, he was said to know all the jutsu from Konohagakure. However, his strength had begun to decrease with his old age, and he was—initially, at least—no match for even his former student, Orochimaru, when the latter led the invasion on Konoha. Also, the Third was burdened with feelings of guilt for not having stopped his former student and being faced with the two previous Hokages that Orochimaru summoned. These factors also contributed heavily to the Third Hokage's reluctance to battle the Snake Sannin with his full heart, as was noted by Enma.
Having no other choice, the Hokage decided to sacrifice his life to seal Orochimaru's soul much like the Fourth Hokage did to the Kyūbi. His old age and weakened state (including, but not limited to, his being impaled upon Orochimaru's (Kusanagi Sword)) did not allow him to seal Orochimaru's whole soul, however, so he chose to only seal Orochimaru's arms, taking away his ability to use ninjutsu and sacrificing his own life.
The third was previously the student of the First and Second Hokage, and the sensei of Orochimaru, Jiraiya and his successor, Tsunade, the Fifth Hokage, who are now known as the Densetsu no Sannin (伝説の三忍, "Legendary Three Ninja").
Trivia
The Third's real surname is Sarutobi (猿飛), and it has been confirmed that this is the name of his clan. His first name is unknown.
It had often been speculated on whether or not the Third was related to Sarutobi Asuma. It was a common speculation that Sarutobi was the Third's first name. In chapter 314 of the manga, it was finally confirmed that Asuma is the Third Hokage's son, and that Sarutobi is his surname.
Sarutobi means "jumping like a monkey", and his Kuchiyose no Jutsu summons an ape.
Monkeys are known usually as a Japanese symbol of wisdom.
"Hokage", made up from the words "Ho" (fire) and "Kage" (shadow). In Chinese, the kanji is read as "Huo" (fire) "ying" (shadow)
Many aspects of his character are borrowed from the Chinese literature classic Journey to the West; the monkey he summons bears a very strong resemblance to Sun Wukong, the protagonist of the Journey to the West, and Sarutobi's chosen weapon is identical to Monkey's magical staff. Incidentally, Dragon Ball Z is heavily influenced from "Journey to the West"
Masashi Kishimoto originally planned for the Third Hokage to be a dog, but eventually dumped the idea for being "too weird". This idea obviously came from the Dragon Ball series, whereas the king of the world is a humanoid walrus-like dog.
According to the official databook his favorite food is dried black seaweed and sardines, and his least favorite pickled vegetables. His hobby is talking with young girls and his favorite phrase is 'the ultimate truth'.
Despite his wisdom the Third seems to have at least some sense of lecherousness to him, as according to a flashback of Jiraiya's, he was quite willing to go with Jiraiya to test out the Toton jutsu (A jutsu invented by Jiraiya for the purpose of voyeurism). Also despite ridiculing it Naruto's Sexy Jutsu is shown to be quite effective against him. He later saw Naruto's Harem no Jutsu and said he would probably fall for it.
Before his death, a crack appeared in his face on the Hokage Monument, noted by Iruka as being a bad omen. Manga artist still make sure to illustrate it every time the mountain is shown up close, but sometimes the animators forget to.
