Skyrim:General Falx Carius

General Falx Carius is an Imperial warrior living in Fort Frostmoth. He carries the enchanted warhammer, Champion's Cudgel, and a Fort Frostmoth key. He wears a set of unique armor, including the cuirass, boots, gauntlets, and helmet, as well as a heartstone necklace (none of which can be looted from his body). Additionally, he will be carrying a Letter to Imperial City if you have not started or progressed his related quest March of the Dead. He can either be accessed by retrieving a key in a knapsack in the deepest room and then unlocking his door, or you can reach him by Whirlwind Sprint from the adjacent tower and entering from the roof of the keep. He will spend all of his time waiting for your arrival in his room.

Carius was posted at the fort around 200 years before the events of Skyrim. When the Red Mountain erupted, he was killed by the debris. As revealed in a journal in the fort, Ildari Sarothril found his corpse and began practicing the black art of necromancy on him, with the intention of utilizing him as a powerful servant for her plot against Neloth. She placed within Carius a heart stone to prevent the effects of the spells from wearing off. It took many weeks of experimentation before Carius showed any sign of response. First he blinked, then he moved, and then he rose. After the initial success of the spells, Carius maintained his free will and attempted to kill her. Out of fear, she removed the heart stone and began further tests, each time faring no better than before. Ildari wanted to gain complete control over him. It can only be assumed that having failed to gain control over General Carius and use him to get revenge on Neloth, Ildari sealed him away inside the fort, as he will be found in a locked room in the fort. Due to Ildari's inability to control him, plus her having no reason to do so, it seems he ordered the attack on Raven Rock himself. He is quite a formidable warrior, especially with his deadly warhammer and the help of his leveled ash spawn minions.     
 
Related Quests
 

Notes
Falx Carius is found in the Bloodmoon expansion for Morrowind as Captain Falx Carius, where he plays a key role in the main questline.
For more information on recurring characters, please see the main article.
Despite being a resurrected corpse, Falx lacks any "undead" keywords, and therefore is not vulnerable to any of the weaknesses associated with other undead. 
During the quest March of the Dead, if you engage the Ash Spawn outside of the fort in the open courtyard without killing all of them, Falx Carius may exit the sealed room and attack you outside the fort without the need to enter the fort to locate and engage him.  This scenario can be reproduced on the PS3 version and occurs after you hear Falx ordering the Ash Spawn to attack while the character is outside of Fort Frostmoth. What seems to trigger this scenario is the summoning of weaker creatures which keep the Ash Spawn busy fighting them instead of you and if the battle goes on for several minutes.
He wears a unique set of armor which cannot be looted.
Since Falx Carius has no level cap and a level multiplier of 1.5, you can never out-level him, and he will always have a significant advantage in health and stamina.
Falx Carius has two points in the Skullcrusher perk, allowing him to ignore 50% of the player's armor. Because of the way Armor Rating functions, this can mean his attacks will potentially deal more than twice as much as the player might expect, making him a particularly fearsome opponent for a high-leveled character with a maxed armor rating.