Which British king changed the family name from Saxe-Coburg-Gotha to Windsor?

George V (George Frederick Ernest Albert; 3 June 1865 – 20 January 1936) was King of the United Kingdom and the British Dominions, and Emperor of India, from 6 May 1910 until his death in 1936.

He was the second son of the Prince and Princess of Wales (later King Edward VII and Queen Alexandra), and grandson of the then reigning British monarch, Queen Victoria. From the time of his birth, he was third in the line of succession behind his father and his own elder brother, Prince Albert Victor.

His reign saw the rise of socialism, communism, fascism, Irish republicanism, and the Indian independence movement, all of which radically changed the political landscape. The Parliament Act 1911 established the supremacy of the elected British House of Commons over the unelected House of Lords. As a result of the First World War (1914–1918), the empires of his first cousins Tsar Nicholas II of Russia and Kaiser Wilhelm II of Germany fell, while the British Empire expanded to its greatest effective extent. In 1917, George became the first monarch of the House of Windsor, which he renamed from the House of Saxe-Coburg and Gotha as a result of anti-German public sentiment.