Lambda
The Greek letter lambda was selected as a symbol by the Gay Activists Alliance of New York in 1970. In December 1974, the lambda was officially declared the international symbol for gay and lesbian rights by the International Gay Rights Congress in Edinburgh, Scotland. The lambda signifies unity under oppression. The gay rights organization Lambda Legal and the American Lambda Literary Award derive their names from this symbol. The lambda was associated with the Spartans because they were also known as the Lacedaemonians.
Read more about this topic: LGBT Symbols