ग्रेट ब्रिटेन अथवा ब्रिटेन यूरोप में स्थित एक द्वीप है। यह द्वीप, यूनाइटेड किंगडम देश का सबसे बड़ा हिस्सा है। इंग्लैंड, स्कॉटलैंड और वेल्स इसी द्वीप पर स्थित हैं।

Great Britain is an island in the North Atlantic Ocean off the north-west coast of continental Europe, consisting of England, Scotland and Wales. With an area of 209,331 km² (80,823 sq mi), it is the largest of the British Isles, the largest European island and the ninth-largest island in the world. It is dominated by a maritime climate with narrow temperature differences between seasons. The island of Ireland, with an area 40 per cent that of Great Britain, is to the west—these islands, along with over 1,000 smaller surrounding islands and named substantial rocks, form the British Isles archipelago.