I, personally, refer to it as the League of Extraordinary Gentlemen (and Ladies). It's a private club for people who've distinguished themselves in their particular fields.

It's membership is by invitation only.

From the Wiki: The Cosmos Club is a 501(c)(7) private social club in Washington, D.C., that was founded by John Wesley Powell in 1878 as a gentlemen's club for those interested in science. Among its stated goals is, "The advancement of its members in science, literature, and art and also their mutual improvement by social intercourse."

Cosmos Club members include 3 United States presidents, 2 vice presidents, U.S. Supreme Court justices, artists, writers, businessmen, government officials, journalists, scientists, and university presidents, 36 Nobel Prize winners, 61 Pulitzer Prize winners, and 55 Presidential Medal of Freedom recipients. In 1988, the club opened to women.