I was born a "Prince of York," became "King of the United Kingdom and the Dominions of the British Empire, and Emperor of India" upon my father's death, died a Duke, but held many other royal titles during my lifetime. Who am I?

I was born a "Prince of York," became "King of the United Kingdom and the Dominions of the British Empire, and Emperor of India" upon my father's death, died a Duke, but held many other royal titles during my lifetime. Who am I?