Marwyn

Captain Marwyn was one of Prince Arthas Menethil's captains during the Third War.

The Third War
Marwyn had known Arthas all his life and saw him not just as his prince, but as a true friend. Marwyn was a close friend of Falric, and a confidant of Prince Arthas. Throughout Arthas' campaigns in the Third War, Marwyn was present to help oversee operations and lead the soldiers. When the time came to strike at Mal'Ganis, Marwyn, Falric, Luc Valonforth and Arthas drove into the heart of Northrend and achieved victory, though not without having first attained Frostmourne.

Eventually, Arthas fell to the whispers of the blade. He murdered many of his soldiers from the 1st Legion, raised them into undeath and turned his two most trusted captains, Falric and Marwyn, into malicious death knights.

Ultimately, Falric and Marwyn accompanied Arthas back to Lordaeron. They stood at Arthas' side as he walked into the throne room and murdered his father. It was Falric and Marwyn who had the task of slaying the citizens of the city, raising them into undeath using their newly gained powers.

Wrath of the Lich King
Marwyn, alongside Falric, made his first appearance in World of Warcraft as a boss of the Halls of Reflection, third wing of the Frozen Halls. They were both killed by the adventurers of the Alliance and Horde.

Shadowlands
During the Scourge resurgence, Marwyn was one of the undead forces reanimated by Mawsworn kyrian in Icecrown Citadel in Icecrown.

Trivia

 * Marwyn wears a purple and yellow version of the death knight tier 10 armor, Scourgelord's Battlegear. This variant is not available to players. It is also worn by Deathbringer Saurfang.
 * Though Marwyn was a corporeal death knight in Reign of Chaos, he appears as a translucent spirit in the Halls of Reflection.