Sannin

The were the students of Hiruzen Sarutobi, members of his Team Hiruzen: Jiraiya, Orochimaru, and Tsunade. They possess exemplary ninja abilities. When they were young and relatively unknown during the Second Great Shinobi World War they fought against Hanzō, and for being able to survive his attacks he gave them the title of Konoha's Sannin in return for letting them live. After that, their names became famous throughout the world.

The Sannin are widely regarded for their great skill and power, each one has the level of being a Kage in their own right; each has been considered for the position of Hokage at different points in time, with one of them obtaining the title. When Orochimaru defected from Konoha after being denied the position, the Sannin were disbanded, though they continued to be known by the title.

Renown

 * Jiraiya, the "Toad Sage," wandered the world, discovered and trained under the toads and wrote the Icha Icha series of novels. Later he became the teacher of Yahiko, Konan, Nagato, Minato Namikaze, and Naruto Uzumaki. Died while investigating Pain but in turn killed his Animal Path in the process. According to the data book, Jiraiya is the strongest of the sannin.
 * Orochimaru, the "White Snake," defected from Konoha, joined Akatsuki, and founded Otogakure. Seeks to gain immortality via means of kinjutsu in order to learn every jutsu in existence. Later he taught Anko Mitarashi and Sasuke Uchiha, the latter who absorbed him, and later sealed away by Itachi Uchiha.
 * Tsunade, the "Slug Princess," granddaughter of the First Hokage and grandniece of the Second Hokage. Possesses terribly unlucky addiction to gambling. Became famous during the ninja wars as the world's greatest medical-nin. Trained Shizune and Sakura Haruno in the art of medical ninjutsu. Took on the title of Fifth Hokage. Currently in a comatose state after running extremely low on chakra when saving Konoha's citizens during the Invasion of Pain.

Trivia

 * Despite being three of the most powerful Shinobi Konoha has ever produced, each of them departed from Konoha for different reasons. Orochimaru left to join Akatsuki and further develop his forbidden techniques, Jiraiya went to gather information on Orochimaru and Akatsuki's movements, and Tsunade lost all confidence in her healing ability and went into self-imposed exile.
 * The Sannin are named after the characters in the Japanese folktale Jiraiya Goketsu Monogatari.
 * Each member of the Sannin has trained a member of Team 7 (not including Kakashi), Orochimaru trained Sasuke, Tsunade trained Sakura, and Jiraiya trained Naruto. Though Minato, Jiraiya's pupil, did teach Kakashi.
 * No Sannin has a surname stated in the series.
 * The world wide game "scissors, paper, stone" originated from China during the Eastern Han Dynasty (25-220), invented by the warlords of that period. Except instead of paper, they used the open palm symbol to represent cloth, so it's "Scissors, Stone, Cloth". The game reached Japan in the early 1640s and one variation of the game was the "Slug, Snake, Frog" variation. In this variation, the Frog is afraid of the Snake, the Snake is afraid of the Slug, and the Slug is afraid of the Frog. This is influenced by the Sansukumi way of thinking where it keeps the three objects in a deadlock. The fact that the Sannin use these three animals as summons may be the author hinting that there is no stronger one among them, and that their strength is more or less equal.
 * The Sannin have their own nicknames.
 * All of them have at some point fought Naruto.
 * The Sannin are all masters of the Summoning Technique.