Ornstein was one of Lord Gwyn's most trusted knights, who was also loyal to Lord Gwyn's Firstborn. Believed to be the captain of the Four Knights of Gwyn, he was granted a special soul and ring by the Lord of Sunlight.
His golden armor was made to resemble a lion and was imbued with the power of lightning. It is said that his lugged spear could slice a boulder in two. After the gods fled Anor Londo, Ornstein and Executioner Smough were stationed to guard its cathedral, and the princess of sunlight within it.
At some point, Ornstein left the cathedral in search of the Nameless King. It is unclear how Ornstein survived the battle against the Chosen Undead, but it appears he eventually found his way to Archdragon Peak. However, the results of his search, as well as Ornstein's own fate, remains unknown.
- Ornstein seems to hold a consistent presence across all three Dark Souls games in some form or another:
- He appears as a boss alongside Smough in Dark Souls.
- The Old Dragonslayer is a boss in Dark Souls II that dons a black version of Ornstein's armor and utilizes dark magic. Whether the Dragonslayer is Ornstein himself or an imposter is unknown.
- The Dragonslayer Armour takes obvious inspiration behind Ornstein; aside from visual similarities between the two (including the two both possessing a red plume), the Dragonslayer Armour utilizes lightning in some of its attacks. It is also revealed in the Dragonslayer Set description that Ornstein left Anor Londo in search of the Nameless King.
- Ornstein's name, alongside the Leo Ring, are homages to famous Russian-American composer, Leo Ornstein, an experimental composer of the early 20th century.