The X Club was a dining club of nine men who supported the theories of natural selection and academic liberalism in late 19th-century England. Thomas Henry Huxley was the initiator; he called the first meeting for 3 November 1864. The club met in London once a month—except in July, August and September—from November 1864 until March 1893, and its members are believed to have wielded much influence over scientific thought. The members of the club were George Busk, Edward Frankland, Thomas Archer Hirst, Joseph Dalton Hooker, Thomas Henry Huxley, John Lubbock, Herbert Spencer, William Spottiswoode, and John Tyndall, united by a "devotion to science, pure and free, untrammelled by religious dogmas."
The nine men who would compose the X Club already knew each other well. By the 1860s, friendships had turned the group into a social network, and the men often dined and went on holidays together. After Charles Darwin's On the Origin of Species was published in 1859, the men began working together to aid the cause for naturalism and natural history. They backed the liberal Anglican movement that emerged in the early 1860s, and both privately and publicly supported the leaders of the movement.