William Dresari was a noble from the Federated Suns world of Kentares IV. William was the cousin of Ian Dresari and nephew of Eric Dresari and Peter Dresari. When Kentares IV was occupied by Lyran Alliance forces led by Lord Marcus Roland, William openly supported the Lyrans in a blatant attempt to overthrow his own family and make himself Duke of Kentares. In recognition of William's pro-Steiner allegiance, the betrayal of his family, and offering to assist in eliminating resistance against the occupation forces, Lord Roland appointed William as Duke.
In his propaganda broadcasts to the people of Kentares, Roland claimed that his actions were in the name of "Duke William".
William was a highly competent MechWarrior. He informed Lord Roland that his 'Mech was being transported to the front lines and he would help Roland hunt down Sir Peter Dresari with the assistance of Captain (Kommandant) Duncan Burke.
In his private communiques with Ian, William bragged how he had betrayed their family by telling Roland how to capture the Dresari family and even had a hand in the murder of his uncle Peter. William even attempted to bribe Ian to end hostilities by offering him a position of power on another planet or even a noble serving House Steiner on Kentares. Needless to say, Ian was not impressed and immediately terminated the comlink with William.
Just after Ian Dresari captured the Ducal Palace, William challenged Ian to a 'Mech duel to the death, all the while berating Ian for ruining William's plans. Ian managed to destroy William's customized Daishi OmniMech, killing him.
 Behind The Scenes
William was portrayed by actor Evan Helmuth.
- MechWarrior IV: Vengeance Video Game.