A Roman senator who became a general in the war between Arthur and Lucius Hiberius. He was present at the first battle, which began after Gawain cut off a Roman warrior’s head during peace negotiations. Gawain and his companions—fearful at how Arthur might react to their actions—concentrated on capturing Petreius Cotta to soothe Arthur’s anger when they returned to him; Boso managed to accomplish this arrest. Without their leader, the Roman brigade fell apart. Arthur was indeed pleased with his prisoner, he and threw him into a Paris jail. An attempt by the Romans to rescue him failed.