A German maiden whom King Locrinus of Britain had captured. He wanted to marry her, but was forced to marry Gwendolen, daughter of Corineus of Cornwall. Estrildis was his mistress for seven years and bore him a daughter named Habren. When Corineus died, Locrinus put Estrildis on the throne as his queen, which made Gwendolen to return to Cornwall and raise an army.

Locrinus was killed by an archer and Gwendolen gave orders to drown Estrildis and Habren in a river, and that the river should hereafter carry her name. The Romans called the river Sabrina, and today it is known as the River Severn.