Alexander I (called "of Jülich"; French: Alexandre de Juliers, Dutch: Alexander van Gulik) was the prince-bishop of Liège from 1128 to 1134.
As bishop, he received the Pope Innocent II, the Emperor Lothair II, and Bernard of Clairvaux. As prince, he was a warrior, taking part in the wars of Waleran, Duke of Lower Lorraine, against Godfrey I of Leuven.