Oscar, Knight of Astora

Oscar is a knight of Astora and plays a minor role in the Dark Souls story. He is equipped with full Elite Knight armor, a Crest shield, and a long sword.

Plot
Spoilers Ahead!

Oscar appears in the very beginning of the game in the Undead Asylum, where he rescues the player character from incarceration by dropping a corpse with the jail cell key down the roof of the player's jail cell. He is later found dying (presumably mortally injured by the boulder rolled down the stairs by the hostile hollow), where he gives the player character five estus flasks (and, if the player had defeated the asylum demon in the first encounter, the key to escape the Asylum). He then dies.

Oscar is encountered again upon revisiting the Undead Asylum, as an hollow enemy. He drops the Crest shield and two thousand souls upon defeat.

Strategy
Oscar alternates between using his long sword two-handed and single handed, and kicking the player for heavy stamina reduction. His attacks are somewhat painful, but he also moves slowly for an NPC enemy, allowing for plenty of opportunities to heal. He has the heavy roll, making it easy to strafe him. Also, unlike other hollows, he does not heal. However, he also has very high amounts of hitpoints and it may take a while to chip his health down unless the player is bringing a good weapon or spells.

Trivia
Judging from the Elite Knight Armor description, Oscar is likely a high-ranking knight from Astora.