Hokage

The are the leaders of Konoha. They are generally the strongest in the village, although ideology and renown plays a large part in their being chosen for the position.

Five shinobi and one kunoichi have gained this title so far. When the position for Hokage becomes open, whether because of the previous Hokage's death or incapacitation, the Konoha Council promptly begins to search for a replacement,in some cases within hours or days after a Hokage has been deemed dead or unfit; this can be seen in the case of Tsunade after she slipped into a coma.

After being appointed, they are given the Hokage mansion in which to live and have their faces carved out in the stone wall behind it. Though she was pointed out during the first part of the series, the Fifth Hokage's face was not carved out before the beginning of Part II.

According to Kakashi, once a shinobi has been appointed by the Konoha Council it is up to the Jōnin of the village to determine whether the position will become official.

Sixth Hokage
Danzou is a candidate for the Sixth Hokage's place. He also attend the Five Kage Summit. Now, knowing Danzo is an undependable person Kakashi is the new candidate for the Sixth Hokage. The official Sixth Hokage is yet to be known.

Trivia

 * All of the former Hokage, except for Tsunade, have been sealed away in the stomach of the Death God summoning; The Fourth was sealed when he sealed the Nine-Tailed Demon Fox within Naruto, while the First and Second were re-sealed when the Third sealed them away. As for the Third, he was sealed when he gave his life to seal Orochimaru, but only managing to seal away his arms.
 * All Hokage have had some connection to each other: The First and Second were brothers, the Third was the student of the Second, The Fourth was the student of Jiraiya who was a student of the Third, and the Fifth was the granddaughter of the First, the grandniece of the Second, and the student of the Third. When Kakashi was considered for the position of the Sixth, his connections to the past Hokage almost cemented his selection as he was a student of the Fourth. The current acting Hokage, Danzō, was once a rival to the Third for the position, and Danzō disagrees with the peaceful ideologies of the previous five Hokages.
 * At least three of the Hokage are descendаnts of the Senju clan.
 * In Naruto Ultimate Ninja 3, Naruto became the Hokage for one whole week.