A (First Raikage)

The was the one who founded Kumogakure in the Land of Lightning.

Background
At the first meeting of the five Kage, he was accompanied by the future Second Raikage. He sat alongside the other Kage and told Hashirama that bowing to other Kage was not a sign of a lasting leader. After asking the First Kazekage to give voice to his alternative request, since Sunagakure already had a tailed beast, he expressed outrage when the Kazekage made a demand of receiving 30% of whatever they would pay for a tailed beast from Konoha. As infighting broke out and Hashirama Senju made his plea to them to preserve the future of their children and unite, he looked on intently.

Personality
While not much was seeing of his personality, the First did seemingly have a verbal tic, ending his sentences with. He also seemed to have a habit of folding his arms. Like his future successor, A, he held the idea that shinobi shouldn't lower their heads so easily.

Appearance
The First Raikage was a dark-skinned man, with prominent creases under his eyes and a mop of shaggy black hair, which partially obscured his headband. In terms of attire, he wore a high-collared dark kimono-shirt, dark pants bound by a sash and a light-coloured scarf around his neck. He also wore small stud-earrings.

Infinite Tsukuyomi Arc
Subsequent to Kaguya Ōtsutsuki being sealed by Naruto Uzumaki and Sasuke Uchiha, he and the other deceased Kage were summoned from the Pure Land by Hagoromo Ōtsutsuki to aid him and the Hokage in summoning Team 7, the tailed beasts and Madara Uchiha's discarded corpse from Kaguya's dimension.

Trivia

 * In terms of appearance, the First Raikage bears a stark resemblance to popular African-American music icon Jimi Hendrix.