Fado is the King of Renais, he dies in the siege of Renais Castle in the early part of Fire Emblem: The Sacred Stones. He is the father of both Lord characters, Eirika and Ephraim.
In the Creature Campaign, you can get him (as a General) if you clear the Lagdou Ruins in its entirety once.
Trivia
In the cutscene he is featured in, his sprite is that of the unused Peer class also used in cutscenes by Elbert in Fire Emblem: Rekka no Ken. However, his sprite is changed to a General in the Creature Campaign.