John Smith Athelstane GCC (9 May 1813 – 16 April 1886) was a British diplomat, author, biographer and painter.

In 1852, he bought the Quinta da Carnota, an ancient convent near Refugidos, Cadafais (Alenquer), and established his life and work there.

In 1871, he republished that work with the new title The Marquis of Pombal by the Conde da Carnota with several changes to its content.

[3] On 9 August 1870, King Luís I of Portugal gave John Smith Athelstane the title of Conde da Carnota.

He was married on 30 April 1850 in England to Miss Anne Tilby, who later died at the Quinta da Carnota on 7 November 1856, and was buried in that property.