Kekkei Genkai (血継限界, kekkei genkai) is an ability from the manga series Naruto that was created by Masashi Kishimoto. It first began serialization Shueisha's Weekly Shonen Jump in November 1999. It first appeared in Naruto Volume 2, CH. 12 "Game Over!!!". There are however various forms of Kekkei Genkai that appear through the run of the Naruto series at various points.
Dōjutsu (瞳術, dōjutsu) are genetic traits that effect the eyes of those who inherit it. There are three known type of dōjutsu. Though these eyes are normally passed down through bloodlines, it has been shown to be possible to transplant the eyes into a person who doesn't share the same blood and still retain the same abilities.
The Byakugan (白眼, byakugan)
The Sharingan (写輪眼, sharingan)
It first appeared in Naruto Vol. 2 Ch. 412 "Game Over!!!".
The Rinnegan (輪廻眼, rinnegan)
The Nature Transformation (性質変化, Seishitsu Henka)
The Kekkei Tōta (血継淘汰, kekkei tōta) is an extremely rare form of kekkei genkai.