William Sinclair (rector)

William Sinclair (4 September 1804 – 8 July 1878) was a Scottish author and rector of St George's Church, Leeds, and of Pulborough, Sussex.

Sinclair was the fifth son of Sir John Sinclair of Ulbster, 1st Baronet by his second wife Diana, only daughter of Alexander Macdonald, 1st Baron Macdonald. His siblings included Catherine Sinclair, George Sinclair and John Sinclair. He was educated at Winchester College but left at the age of sixteen, obtained a commission in the Madras cavalry, and distinguished himself by leading a forlorn hope at the siege of Kittoor in 1824.

Returning to England, he matriculated at St Mary's Hall, Oxford, in 1832, and graduated B.A. in 1835 and M.A. in 1837. At Oxford he became president of the Union when it numbered among its members Archibald Tait, Roundell Palmer, Edward Cardwell, and Robert Low. In 1833 Thomas Jackson composed a squib Uniomachia, or The Battle at the Union and later said that Sinclair "entered heartily into the scheme, and composed many of the best lines and notes".