(24 Dec. 1046–9 Oct. 1047)
Originally named Suidger, as bishop of Bamberg, in Bavaria, he accompanied King Henry III of Germany (1039–56) to Italy in autumn 1046 and, after the deposition of Silvester III, Gregory VI, and Benedict IX on 20 and 24 Dec., was elected pope on the nomination of the king, the first of four German popes he was to impose. Henry's first choice had been Adalbert, archbishop of Hamburg–Bremen, who declined. Suidger had long enjoyed the king's confidence. Of noble Saxon stock, he had been canon of Halberstadt, had become chaplain to his provost, Hermann, when he was appointed archbishop of Hamburg in 1032, and after Hermann's death in 1035 had entered the royal chapel. Still a deacon, he was consecrated, on Henry's nomination, bishop of Bamberg on 28 Dec. 1040.
Henry's initiative in rescuing the papacy from feuding Roman families was generally approved in reforming circles. Suidger shared his concern for reform in the church; his choice of the name Clement underlined his resolve to look for inspiration to primitive Christianity. Enthroned on 25 Dec. 1046, he crowned Henry and his queen Agnes as emperor and empress on the same day. Henry then had himself invested with the rank of patrician, which empowered him to take the lead in the appointment of a pope, and the Romans had to undertake afresh not to elect a pope in future without the approval of emperor and patrician. The constitutional issue settled, Clement started his reform programme, presiding on 5 Jan. 1047 over a synod which sharply condemned simony and decreed a 40 days' penance for any who had knowingly been ordained by simoniacal bishops. After the synod he accompanied Henry (mid-Jan.) on his progress to south Italy, at Salerno (18 Feb.) confirming John of Paestum as archbishop after checking that he had obtained the see without simony, and placing Benevento under an anathema when it refused to open its gates to the emperor. At the end of Feb. he returned to Rome, conferring there in the spring or summer with the aged Odilo, fifth abbot of Cluny (d. 1049), and publishing a bull commending his abbey to leading personalities in France. The reformer Peter Damian (1007–72) also wrote to him expressing disappointment at the slow progress of his reforming policies. In late summer he moved to the Marches (some think he had to leave Rome because of serious disturbances there), and on 24 Sept. he issued a bull, lyrical in tone, confirming the privileges of Bamberg, his ‘most sweet spouse’ from whom he could not bear to be separated; in fact he remained its bishop throughout his pontificate. On 1 Oct. he was at the abbey of S. Tommaso, near Pesaro; he was seriously ill and died there on 9 Oct. A rumour, soon in circulation, that he had been poisoned by Benedict IX is probably groundless. His body was taken to Bamberg and buried in his cathedral, the only papal tomb north of the Alps. When the tomb was opened on 22 Oct. 1731, he was found to have been a man well over six feet tall with yellow hair. It was again opened on 3 June 1942 and the remains subjected to an exhaustive examination which disclosed that he probably died of lead poisoning.