Sigurd Snake-in-the-Eye was a legendary Viking hero, son of Ragnar Lothbrok, known for a unique serpent ( Ouroboros) mark in his eye, signifying greatness and destiny, making him a fierce warrior, leader, and key figure in avenging his father's death. He became a ruler of Denmark, a king whose descendants were influential, and a man whose life blended bravery, vengeance, and mystical lineage, often depicted as bold and sometimes rash, with a legendary connection to dragons.

Key Characteristics & Story
The Mark: Born with a serpentine pattern around his pupil, resembling the Ouroboros (a snake eating its tail), a symbol of eternity and magic, linking him to the dragon-slayer Sigurd Fafnisbani and the world serpent Jörmungandr.
Father & Vengeance: A close companion to Ragnar, he was deeply involved in avenging his father's death by King Ælla, forming the Great Heathen Army with his brothers.
Warrior & Ruler: A formidable warrior and leader, he became King of eastern Denmark, ruling significant territories like Sjælland, Skåne, and Halland, marrying Ælla's daughter and founding a royal Danish line.
Personality: Described as bold, decisive, and possessing unique insight, sometimes influenced by his unique birthmark, leading to both heroism and internal conflict, especially in adaptations like the Vikings series.
Legacy: His story highlights themes of destiny, family loyalty, and the magical side of Viking legend, cementing his place as a significant, if semi-legendary, figure in Norse lore.