Thyra was the wife of King Gorm the Old of Denmark, and one of the first queens of Denmark widely believed by scholars to be historical rather than legendary. She is presented in medieval sources as a wise and powerful woman who ordered the building or fortification of the Danevirke, consistent with her commemoration on multiple Viking Age runestones. These include those at Jelling which was the seat of power for her dynasty. When she was born and became queen is unclear, however, she likely ruled until her death in the middle of the 10th century CE.

Gorm the Old, also called Gorm the Languid, was ruler of Denmark, reigning from c. 936 to his death c. 958 or a few years later. He ruled from Jelling, and made the oldest of the Jelling stones in honour of his wife Thyra. Gorm was born before 900 and died perhaps around 958 or possibly 963 or 964.