The Fourth is one of the greatest Hokage in the leaf village but at the time the story began he's already a legend as he gave his life to save the village from the 9 tail. The Fourth ability is to move very fast and even warp himself to wherever he wanted this made him earn the nick name of Konoha Yellow Flash. The fact that he is Naruto's Father wasn't known until recently when he shows up at the time the seal on Naruto break. But the mystery still not solve about his background and Naruto's Mother.The Fourth ability is time space manipulation and is very similar to the head of the Akatsuki "Uchiha Madara". And the rumor that somehow The Fourth body was somehow became Madara's might be the cause of that similarity. Also that a few people said that the fourth himself is the leader of the Akatsuki. But this rumor spread before Madara made his claim to the Akatsuki and reveal his plan to the world of shinobi.
There are also rumor about Uchiha Madara is really Tobi, the childhood friend of Kakashi Hatake. Maybe because of him only posses one eye as the other have been given to Kakashi. And the fact that the two of the posses the same type of ability that is to use space time manipulation jutsu. Madara can move out and in the battle field with no trouble while Kakashi's Jutsu "Kamui" can do something that is similar which is to warp someone or something out of the battlefield. Those similarity seems to trigger people perception to think that the three of them actually connected for some reason still waiting to be revealed.
