Harold I, also known as Harold Bluetooth, was the King of Denmark from 958 to 986. He is credited with uniting Denmark and Norway under the banner of Christianity. There are a few synonyms for Harold I that you may come across in historical documents and literature. Some of these include Harald Bluetooth, Harald I, Harald Gormsson, Bluetooth Harald, and Harald the Noisy. These different references to Harold I may be used depending on the context or the time period in which they were written. Regardless of the name used, Harold I remains an important figure in Danish history and served as a leader and unifying force during his reign.