Grendel of Gracht

Count Grendel of Gracht was a Taran count and the owner of Castle Gracht. He imprisoned Tara's rightful ruler, his cousin Prince Reynart, in Castle Gracht, along with Princess Strella.

Plot for kingship
Grendel wanted to be king of Tara. He took Reynart prisoner to prevent him from being crowned, whereupon Grendel would be chosen to replace him. However, the Fourth Doctor used an android to substitute for the prince. Grendel decided to force Romana, who was identical in appearance to Strella, to marry Reynart. Grendel would then kill the king and marry his widow, becoming king. The Doctor arrived at the wedding and revealed the count's plot, challenging Grendel to a sword fight. Grendel lost the fight, dived from the battlements of Castle Gracht into the moat and swam away. He was exiled by Reynart. (DW: The Androids of Tara)

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