He was Konoha's 4th Hokage, Yondaime, and he was known in all the ninja villages as "Konoha's Yellow Flash" because he was so fast and powerful. Enemies of Konoha were told to not fight him, but run if they ever met him.
He was trained by Jiraiya, one of the three great sannin, and later became the sensei of Kakashi Hatake, Obito Uchiha and Rin.
Later in the manga (and now also in the anime) it has been made clear that he was in fact Naruto's father. He sealed the Kyuubi inside of Naruto when he was a new born, because he thought that this was the only way to protect his village and the people that he loved. Unfortunately, Minato died whilst doing this. He was a true hero.
Minato Namikaze is my favorite fictional character of all time.
Minato Namikaze was a true shinobi.
If Minato Namikaze hadn't died that day, Naruto would've still had his dad.