missionary to the Prussians, bishop, and martyr.

A member of the family of the counts of Querfurt, Bruno was educated at the cathedral school at Magdeburg, Saxony, and at the age of 20 he was attached to the clerical household of the Holy Roman emperor Otto III. In 997 he accompanied Otto to Rome, where he was influenced by St. Romuald toward severe asceticism. When news reached Rome of the martyrdom of St. Adalbert (Adalbert, Saint), bishop of Prague (997), Bruno entered the monastery of SS. Bonifazio ed Alessio, taking the name of Boniface.

Otto founded a monastery for Bruno and Romuald at Pereum near Ravenna in 1001, from which Bruno carried on Adalbert's mission of Christianizing the pagan Prussians by first sending a small mission (the “Five Martyred Brothers”), including Saints Benedict and John, to Poland. The party was slaughtered en route. Subsequently, Bruno wrote their biographies, and, after being appointed archbishop by Pope Sylvester II, he visited the sovereigns of Germany, Hungary, and Ukraine in quest of aid for his missionary activities.

During his stay in Hungary (1004), Bruno wrote the best of the three extant biographies of Adalbert. He was so successful in converting the pagan Pechenegs, who inhabited the country between the Don and the Danube rivers, that they made peace with Vladimir and were for a while nominal Christians. Determined to proceed with his Prussian mission, Bruno set out with 18 companions, but they were massacred by the heathens.