Harold Bluetooth Gormson (Danish: Harald Blåtand, Old Norse: Haraldr blátönn, Norwegian: Harald Blåtann), was born 911 as the son of King Gorm the Old (king of Jutland, i.e. pensinsular denmark) and of Thyra (Thyre) Danebold d.986, was King of Denmark from around 958 succeeding his father and mother until his own death, and king of Norway for a few years probably around 970.

His biography is summed up by this runic inscription in Old Norse:
"Haraltr kunukr bath kaurua kubl thausi aft kurm fathur sin auk aft thaurui muthur sina. sa haraltr ias sar uan tanmaurk ala auk nuruiak auk tani karthi kristna"

Translation:
"Harald, king, bade these memorials to be made after Gorm, his father, and Thyra, his mother. The Harald who won the whole of Denmark and Norway and turned the Danes to Christianity".

During his reign, Harald oversaw the reconstruction not only of the Jelling runic stones but of other projects as well. Some believe that these projects were a way for him to preserve the economic and military control of his country.

He also constructed the oldest known bridge in southern Scandinavia, known as the Ravninge Bridge. It was built in Ravninge meadows, and was 5m wide and 760m long.

Harald had a son named Sweyn (Forkbeard), who was baptized along with the rest of the royal family, and given the name of the Holy Roman emperor Otto the Great:

“Not long after Harold himself was baptized together with his wife, Gunnhild, and his little son, whom our king raised up from the sacred font and named Svein.”

While absolute quiet prevailed throughout the interior, he was even able to turn his thoughts to foreign enterprises. Again and again he came to the help of Richard the Fearless of Normandy (in the years 945 and 963), while his son conquered Semland and, after the assassination of King Harold Graafeld of Norway, he also managed to force the people of that country into temporary subjection to himself. The Norse sagas presents Harald in a rather negative light.

As a consequence of Harald's army having lost to the Germans in the shadow of Danevirke in 974, he no longer had control on Norway and Germans having settled back into the border area between Scandinavia and Germany. The German settlers were driven out of Denmark in 983 by an alliance consisting of Obodrite soldiers and troops loyal to Harald. Soon after, Harald was killed fighting off a rebellion led by his son Sweyn. He was believed to have died in 986, although there are many other accounts that claim he died in 985.

He died 1 November, 985 or 986. His remains were buried in the cathedral at Roeskilde, where his bones are still preserved, walled up in one of the pillars of the choir.