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?

Edward VIII ( born Edward Albert Christian George Andrew Patrick David; 23 June 1894 – 28 May 1972) was King of the United Kingdom and the Dominions of the British Empire, and Emperor of India, from 20 January 1936 until his abdication on 11 December the same year.

The many titles and styles of Edward VIII

23 June 1894 – 28 May 1898: His Highness Prince Edward of York

28 May 1898 – 22 January 1901: His Royal Highness Prince Edward of York

22 January – 9 November 1901: His Royal Highness Prince Edward of Cornwall and York

9 November 1901 – 6 May 1910: His Royal Highness Prince Edward of Wales

6 May – 23 June 1910: His Royal Highness The Duke of Cornwall

23 June 1910 – 20 January 1936: His Royal Highness The Prince of Wales

(in Scotland: His Royal Highness The Prince Edward, Duke of Rothesay)

20 January – 11 December 1936: His Majesty The King

(occasionally, with regard to India: His Majesty The King-Emperor)

11 December 1936 – 8 March 1937: His Royal Highness The Prince Edward

8 March 1937 – 28 May 1972: His Royal Highness The Duke of Windsor

If interested you can research all the details here: https://en.wikipedia.org/wiki/Edward_VIII