Great Britain was not colonized by another country. Instead, it was the British Empire that established colonies in various parts of the world. The British Empire was one of the largest and most influential empires in history, and it included colonies in North America, the Caribbean, Africa, Asia, and Oceania, among other regions.
Great Britain itself was the core of the British Empire, and it served as the colonial power, establishing and governing colonies in different parts of the world. Over time, many of these colonies gained independence, leading to the formation of various modern nations. So, rather than being colonized, Great Britain was the colonial power in the British Empire.