Baldwin I of Jerusalem, formerly Baldwin I of Edessa, born Baldwin of Boulogne (French: Baudouin de Boulogne), c.1058 ??2 April 1118, was one of the leaders of the First Crusade, who became the first Count of Edessa and then the second ruler and first titled King of Jerusalem.

He was the brother of Godfrey of Bouillon, who was the first ruler of the crusader state of Jerusalem, although Godfrey refused the title of 'king' which Baldwin accepted.