Karl Heinrich Ulrichs is considered the first gay person to speak publicly about homosexual rights. He was a lawyer in Germany until he was forced to resign in 1857 on account of his homosexuality.

He became an activist and published 12 volumes of work about sexuality under the title The Riddle of "Man-Manly" Love and included what’s believed to be the first theory about homosexuality. He argued that it is an ‘inborn condition’ not a learned corruption, as was the prevailing wisdom at the time.

Ulrichs is thought to have been the first gay person to publicly speak out for homosexual rights. In 1867, he urged the German government to repeal anti-homosexuality laws, which firmly established him as the pioneer of the gay rights movement.