Grendel of Gracht

Count Grendel of Gracht was a Taran count and cousin of Tara's rightful ruler, prince Reynart, whom he had imprisoned, along with princess Strella.

Plot for kingship
Grendal wanted to be king of Tara. He took Reynart prisoner to prevent him from being crowned, whereupon he would be chosen to replace him. However the Fourth Doctor used an android to substitute for the prince. Grendal decided to force Romana, who was identical to Strella, to marry Reynart. Grendal would then kill the king, and marry his widow. Grendal would then kill her and become king. The Doctor arrived at the wedding and revealed the count's plot. He challenged Grendal to a sword fight and Grendal lost; he jumped into a moat and swam away. Following this, he was exiled by Reynart. (DW: The Androids of Tara)

With the Kandy Man
Grendel later returned, repairing and allying himself with the Kandy Man, who had faced the Doctor in his seventh incarnation. Grendel was once again defeated by the Doctor. (VD: The Trials of Tara)