Paladin

n. one of the twelve knights of Charlemagne; medieval hero; warrior; defender of a cause

A paladin or paladine (derivative terms from palatine, and Latin palatinus, plural palatini) was a high-level official in numerous countries of medieval and early modern Europe.The term paladine was first used in Ancient Rome for a chamberlain of the Emperor, and also for the imperial palace guard called praetorian guard by Diocletian. In the early Middle Ages, the meaning changed and the term was used for one of the highest official of the Catholic Church in the pope's service and also for one of the major nobleman of the Holy Roman Empire, who was in then named Count Palatine. Similar titles were also used in 19th century Hungary and in the German Empire and United Kingdom during the early 20th century.
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Noun
1. someone who fights for a cause
(synonym) champion, fighter, hero
(hypernym) defender, guardian, protector, shielder

n. paladin, one of the twelve knights of Charlemagne; medieval hero; warrior; defender of a cause

n. campaigner; paladin, champion