Sir Guy of Gisbourne was the name of a character from Human mythology. Living in 12th century England, he was a high-ranking official and resided in Nottingham Castle, and together with the High Sheriff of Nottingham was an adversary of Robin Hood.
In a Q-created recreation of the Robin Hood story, Gisbourne had asked Maid Marian to marry him, but had been refused, then ordering her to be beheaded. After Marian (actually Vash) apparently changed her mind, he stopped her execution and presented her as his bride. When the High Sheriff (actually Q) learned of Marian appealing to Robin Hood (actually Jean-Luc Picard) for help, she was arrested again. When both Marian and Robin Hood were about to be executed, Gisbourne proclaimed that both had been found guilty of outlawry and high treason and condemned to death. Before the sentence could be carried out, the Merry Men (Data, Riker, Worf, Troi, and Crusher) intervened. Gisbourne ordered Marian to be taken to the tower; he then engaged in a sword duel with Robin Hood, proclaiming himself to be the greatest swordsman in all of Nottingham, but was ultimately killed by Robin Hood. (TNG: "Qpid")