A (First Raikage)

Birthdate: December 1
Gender: Male
Status: Deceased
Height: 210.1 cm
Weight: 97.2 kg
Blood type: O
Occupation: Raikage
Affiliation: Kumogakure
Manga Debut: Chapter #648
Anime Debut: Naruto Shippuuden Episode #369

A (Viz "Ei", English TV "Ay") was the First Raikage (初代雷影, Shodai Raikage; Literally meaning "First or Founding Lightning Shadow") who founded Kumogakure in the Land of Lightning.

(Source: Narutopedia)