Gwyndolin

The lastborn son of Gwyn and guardian of Anor Londo. Born a Moon Sorcerer, he was raised like a daughter and has a feminine appearance as a result.

Continues his father's instructions to prevent the waning of the Age of Fire, intending for Undead to further fuel the First Flame.

Tall, thin, crown of sun, white clothes, snake feet

Do not enter Gwyn's honorary tomb or else he will come after you, triggering a boss fight. According to the Darkmoon Blade Covenant Ring, the reason why he created the illusion of his sister Gwenevere to help him guarding over Anor Londo is because he's all too aware of his repulsive, frail appearance. An unmasking of these deities would be tantamount to blasphemy.

Gwyndolin considers himself "repulsive". While we can't actually see his face and his snake feet are rather disturbing (and some people might find his enforced femininity disconcerting in a male character), it's hard to call him "ugly" by any stretch. It's likely self-loathing at not measuring up to his father's standards of masculine strength