A colonizer is considered to be a person who is in control (usually in a political way). In The Tempest, Prospero and Caliban are both wanting to be in control. Prospero views himself as better than Caliban. And in turn for his education, Caliban realizes a bit too late that he has turned over his rulership to Prospero, making him the colonizer and Caliban the colonized. This would later lead to even bigger problems.
