Minato Namikaze

Part In The Story
Minato Namikaze, better known as the Fourth Hokage and Konoha's "Yellow Flash", is the ninja responsible for sealing the Nine-Tailed Demon Fox, in Naruto Uzumaki after it attacked Konoha. Sometime before the demon fox's attack, the Fourth met a woman, Kushina Uzumaki, from the former Whirlpool Country. Together they had a child named Naruto Uzumaki, who was born shortly before or on the very night that the demon fox attacked. Minato sealed the demon fox inside Naruto at the cost of his life with the Death God sealing technique of his own design. He carefully designed the seals so that Naruto could slowly become acclimated to the power, and possibly even control it later in his life, providing a key that could unlock the seals. He said that he didn't want Naruto to be viewed as the container of a monster, but as a hero who saved the village from annihilation. Not surprisingly, this request was not honored by the villagers, who still held much resentment for the demon fox.

Minato Namikaze is said to be the greatest ninja Konoha ever produced. Though his skills in combat go largely unwitnessed, he was considered dangerous enough that a flee-on-sight order was given in regards to him during the Third Ninja War, and he has created a number of extremely powerful techniques at a young age. He was a student of Jiraiya along with two other unknown Genin, and was the teacher of Kakashi Hatake, Obito Uchiha, and Rin.

Legacy
Before it was revealed, many people believed that the Fourth was Naruto's father because they share many similarities. For example, they both have the same spiky blond hair, blue eyes, techniques, blood type (B), and overall similar personalities as noted by Jiraiya. Itachi Uchiha noted Naruto to be the Fourth's "legacy". Also, when Jiraiya was trying to force Naruto to release his demon fox chakra, he pushed Naruto off of a cliff, saying, "Forgive me, Fourth," as he did so. Beyond these, there are several minor comparisons made consistently thought the series. Any hints to his name, history, or family relations have been carefully avoided, making his past one of the biggest mysteries of the series until it was finally revealed in Chapter 367.

Personality
Although unknown, Jiraiya points out that Naruto's personality bears great resemblance to the Fourth's. He then says that Naruto shares the personality trait of "pigheadedness" with him. Jiraiya notes that, although he was quite a genius, the Fourth's greatest aspect was his desire to succeed, largely attributing his success to hard work.

Jutsu
The Fourth created several distinctive techniques, including the Flying Thunder God Technique, which essentially allowed him to teleport to any location with the use of a special seal. He also created the Rasengan, a technique that does not rely on hand seals, but instead uses a concentration of spinning chakra in the palm that causes immense damage to its victim on contact. Later in the series it is revealed that this signature technique is actually incomplete. The Fourth had planned to add his own nature manipulation training to the Rasengan, making it even more powerful, but couldn't manage to combine the two prior to his premature death.

Trivia

 * He is also known as "The Leaf's Yellow Flash" (木ノ葉の黄色い閃光)
 * According to Jiraiya, the Fourth is the most skilled Leaf shinobi ever to live.