William Robert Spencer (9 January 1769 – 22/23 October 1834) was an English poet and wit from the Spencer family.
He was the younger son of Lord Charles Spencer and his wife Mary Beauclerk. He was the grandson of Charles Spencer, 3rd Duke of Marlborough on his father's side and Vere Beauclerk, 1st Baron Vere on his mother's. Born in Kensington Palace, Spencer was educated at Harrow School and Christ Church, Oxford, though he left Christ Church without receiving a degree.
Spencer's wit made him a popular member of society. He belonged to the Whig set of Charles James Fox and Richard Brinsley Sheridan and was frequently a guest of the prince of Wales. He did not desire a public life, being content as a writer of "occasional" verse and vers de société. In 1796 he published an English version of Bürger's Leonore, and in 1802 he burlesqued German romance in his Urania, which was produced on the stage at Drury Lane. Among his best-known pieces, which were published in a collection of his poems in 1811, were his well-known ballad "Beth Gelert" and "Too Late I Stayed." His writings were greatly appreciated by his contemporaries, being warmly praised by such figures as Sir Walter Scott, John Wilson, and Lord Byron. 
In 1791 he married Susan, daughter of Count Jenison-Walworth, chamberlain to the elector palatine, by whom he had five sons and two daughters. One son, the Rt Revd Aubrey Spencer (1795–1872), became first Bishop of Newfoundland in 1839, being afterwards translated to the See of Jamaica. Another son, the Rt Revd George Spencer (1799–1866), was in 1837 consecrated second Bishop of Madras.
Spencer briefly sat in the House of Commons but gave up his seat in 1797 in order to become a commissioner of stamps so as to support his family. He held the post until 1826, surrendering it after moving to Paris the year before because of his financial difficulties. Spencer spent his remaining years in Paris, dying there in October 1834. His remains were taken back to England and buried in Harrow Church.
- W. R. Spencer, Poems (London, 1835), containing a biographical memoir;
- The Annual Register (1834)
- Alumni Oxonienses 1715–1886, annotated by J. Foster (4 vols., Oxford, 1891).
- Curry, Charles Madison; Clippinger, Erle Ellsworth (1921). "Beth Gêlert; or, the Grave of the Greyhound" poem by William Robert Spencer Children's Literature  Check |url= value (help). Chicago: Rand McNally. pp. 436–437. Retrieved October 29, 2011.