Knight

A knight was an armored, mounted warrior serving a lord in feudal societies. In the Realms, the term could also refer to, among other things:
 * Eldritch knight, a warrior trained equally in the arts of combat and magic,
 * Triadic knight, a warrior worshiping the Triad as a unit,
 * Purple Dragon knight, a member of the Purple Dragons of Cormyr,
 * Knight of Iron, a knight in service to gnomish deity Gaerdal Ironhand,
 * Knight of the Blue Moon, an elite knight of Waterdeep,
 * Knight of the Flying Hunt, an elite defender of Nimbral,
 * Knight of Silver, a member of the army of Silverymoon
 * Knight of Holy Judgment, a paladin in service to Tyr,
 * Knight of the Merciful Sword, another type of paladin in service to Tyr,
 * Knight of Ilmater, a paladin in service to Ilmater,
 * Knight of Myth Drannor, a member of a famous adventuring company,
 * Knight of Samular, another type of paladin in service to Tyr,
 * Knight of the Black Gauntlet, a crusader in service to Bane,
 * Knight of the Bleeding Shield, a member of another order in service to Ilmater,
 * Knight of the Eternal Dragon, someone dedicated to the destruction of Xavarathimius,
 * Knight of the Golden Star, a warrior in service to Corellon Larethian,
 * Knight of the Weave, a warrior worshiping the Weave itself,
 * Knight of the Shield, a member of a secret society based in the Lands of Intrigue,
 * Vengeance knight, an elite fighter in service to the Knights of the Shield,
 * Silverhair Knight, a priest in service to Eilistraee,
 * Death knight, a powerful undead warrior,
 * Darksong Knight, another kind of warrior in service to Eilistraee,
 * Thayan knight, a general of the army of Thay
 * Griffon Knight, a defender of the town of Alamontyr,
 * Night of the North, a secret society of adventurers from the Moonsea region,
 * Warlock Knight, one of the lords of Vaasa, or
 * Moon Knight, a warrior in service to Sehanine Moonbow.

It could also refer to a specific type of character in various editions of the Dungeons & Dragons rules:
 * Knight (class), a class in 3rd edition,
 * Knight (build), a fighter build in 4th edition, or
 * Knight (nonplayer character), a generic nonplayer character in 5th edition.