Pope Leo IX (d. 1054)
Pope Leo IX (21 June 1002 – 19 April 1054), born Bruno of Egisheim-Dagsburg, was the head of the Catholic Church and ruler of the Papal States from 12 February 1049 to his death in 1054. Leo IX is considered to be one of the most historically significant popes of the Middle Ages; he was instrumental in the precipitation of the Great Schism of 1054, considered the turning point in which the Catholic and Eastern Orthodox Churches formally separated. He is venerated as a saint in the Catholic Church.

Leo IX favored traditional morality in his reformation of the Catholic Church. One of his first public acts was to hold the Easter synod of 1049; he joined Emperor Henry III in Saxony and accompanied him to Cologne and Aachen. He also summoned a meeting of the higher clergy in Reims in which several important reforming decrees were passed. At Mainz he held a council at which the Italian and French as well as the German clergy were represented, and ambassadors of the Byzantine emperor were present. Here too, simony and the marriage of the clergy were the principal matters dealt with. He is regarded as a saint by the Catholic Church, his feast day celebrated on 19 April.