He is based on a real person who created the Cossack Hetmanate in 1648.
His full name was Bohdan-Zinoviy Mykhaylovych Khmelnyts'kyy (Ukrainian: Богдан-Зіновій Михайлович Хмельницький, Polish: "Bohdan Zenobi Chmielnicki"). He belonged to the "Syrokomla" coat-of-arms, depicted in-game as his personal banner.
He was baptized by one of his middle names - Theodor (Ukrainian: Богдан - "Bohdan") - as was custom in the Greek Orthodox Church.
Although the Hetman was the highest military office and head of state in the Cossack Hetmanate, Khymelnyts'kyy was technically not a monarch since a Hetman was - after the monarch - the second-highest military commander in the Polish Commonwealth.