Bagsecg (died January 8, 871) was a Viking leader referred to as a 'King', He is also known as Bægsecg or Bagsec. In 870 or 871 he came from Scandinavia to England, and led The Great Summer Army to England and added his forces to the Great Heathen Army which had already overrun much of England. He and Halfdan Ragnarsson became the joint leaders of a Viking invasion of the Kingdom of Wessex. However he was killed at the Battle of Ashdown, fighting a West Saxon Army led by the king's younger brother, the future Alfred the Great.