Ogma

Oguma is a hard-edged mercenary. He was a gladiator at first and was drafted to the Talisian army when Sheeda stopped several people to punish him. Oguma dedicates his life to be the bodyguard of the princess and was eventually handpicked as the guard of both her and Marth during the latter's quest.

In Fire Emblem: Monshō no Nazo, Oguma allied with General Lawrence in protecting two Grunian noble children: Yubello and Yumina. He caught up with them and protected them throughout a valley full of vikings, with the help of a mysterious knight named Sirius. Later, he joins up with Marth once more, but vanishes once the whole battle is over.

Archtype
Oguma is the first mercenary character in the game and usually has good growths, making him a fan favorite. He also started an Archtype, in which a mercenary or other sword weildeing unit joins early to the middle of the game and have balanced stat growths, and can become some of the best units in the game.