The Great King is an important figure in D'ni legend, whose coming was phrophecied long before he was actually born. Even during his lifetime he was a legendary figure. His importance was not in who he actually was, but rather in who the phrophecies made him be.

Ahlsendar was the son of the D'ni King Koreen. When rebellion broke out in D'ni, led by the breakaway sect known as the Judges, who had gained support from the outworlder Pento people, Koreen was killed. Ahlsendar at the time was in a Private Age, and remained behind. Contacts in D'ni kept him informed of happenings, and while the Judges and Pento began fighting among themselves, Ahlsendar prepared for his return.

After a civil war broke out under the Pento, Ahlsendar saw his chance to reclaim D'ni, and quickly conquered the city. Ahlsendar gained the support of one faction of the Pento in their civil war, and defeated the leader of the other party in single combat. After this, the war was ended, and Ahlsendar was crowned King.

Years later another Pento rebellion occurred, and Ahlsendar's wife and children were killed. In retaliation, Ahlsendar unleashed a deadly engineered plague on the Pento homeworld, killing their entire population. Initially the fact Ahlsendar had himself ordered this plague to be devised was kept hidden, but three decades later he admitted the fact, and repented by relinquishing his crown to his chosen heir Solath.

Ahlsendar asked to be locked in the Temple of the Great King (which had been built many years before), together with all Books infected by the plague. Two years later the Temple was renamed the Tomb of the Great King.

Ahlsendar was recognised as the Great King because his life turned out almost exactly according to the phrophecies. After his apparent death he was for long almost deified by the D'ni, but much later his legacy was mostly forgotten, and the Tomb was buried beneath the Guild Hall. Up until the destruction of the empire there remained however a faction which believed in the Great King.