Alexander II (died April 21, 1073), born Anselmo da Baggio, was Pope from 1061 to 1073.

He was born in Milan. As bishop of Lucca he had been an energetic coadjutor with Hildebrand in endeavouring to suppress simony, and to enforce the celibacy of the clergy. His election, which Hildebrand had arranged in conformity with the decree of 1059 (see Pope Nicholas II), was not sanctioned by the imperial court of Germany. This court, true to the practice observed by it in the preceding elections, nominated another candidate, Cadalus, bishop of Parma, who was proclaimed at the council of Basel under the name of antipope Honorius II (1061–72), marched to Rome, and for a long time threatened his rival's position. At length, however, he was forsaken by the Germanic court and deposed by a council held at Mantua; and Alexander II's position remained unchallenged.

In 1065, he admonished Landulf VI of Benevento "that the conversion of Jews is not to be obtained by force."

In 1066, he entertained the embassy from William the Conqueror which had been sent to obtain his blessing for the Norman conquest of England. This he gave to them, gifting to them a papal ring, the standard of St. Peter, and a papal edict to present to the English clergy saying that William was given the papal blessing for the bid for the throne. These favours were instrumental in the submission of the English church and people following the Battle of Hastings.

Alexander II oversaw the suppression of the 'Alleluia' during the Latin Church's celebration of Lent. This is followed to this day, and in the Tridentine rite 'Alleluia' is also omitted during the pre-Lenten season.

Alexander II was followed by his associate Hildebrand, who took the title of Gregory VII (1073–85).