The Gulidjan, also known as the Colac tribe, Colijan, Colagdians, Kolakgnat, are an indigenous Australian tribe whose traditional lands cover the Lake Colac region of Victoria, Australia. They occupied the grasslands, woodlands, volcanic plains and lakes region east of Lake Corangamite, west of the Barwon River and north of the Otway Ranges. Their territory bordered the Wada wurrung to the north, Djargurd Wurrung to the west, Girai Wurrung to the south-west, and Gadubanud to the south-east.