King Harold I was the first ruler of Denmark from 936 until his death in 940. He is also referred to as Harold Bluetooth, which signifies his great influence in bringing about the acceptance of Christianity in Denmark. Some other synonyms for King Harold I include Harald Blåtand, Harald Gormsson, and Harald Greycloak. Harald Blåtand, which translates to "Bluetooth", is the name with which he is most commonly known. Harald Gormsson relates to his father, Gorm the Old, and Harald Greycloak refers to his cloak's color. King Harold I's reign was marked by implementing policies that brought social, political, and religious stability, which led to his lasting legacy.