The pink triangle has been a symbol for various LGBT identities, initially intended as a badge of shame, but later reclaimed as a positive symbol of self-identity.

It began as one of the Nazi concentration camp badges, distinguishing those imprisoned because they had been identified by authorities as homosexual men, a category that also included bisexual men and transgender women. In Nazi concentration camps, each prisoner was required to wear a downward-pointing, equilateral triangular cloth badge on their chest, the color of which identified the reason for their imprisonment. The pink triangle was established for prisoners identified as homosexual men, which also included bisexual men and transgender women. If a prisoner was also identified as Jewish, the triangle was superimposed over a yellow second triangle pointing the opposite way, to resemble the Star of David like the yellow badge identifying other Jews. Prisoners wearing a pink triangle were harshly treated, even by other prisoners.

After the camps were liberated at the end of the Second World War, many of the prisoners imprisoned for homosexuality were re-incarcerated by the Allied-established Federal Republic of Germany. The Nazi amendments to Paragraph 175 turned homosexuality from a minor offense into a felony, remaining intact in East Germany until 1968 and in West Germany until 1969. West Germany continued to imprison those identified as homosexual until 1994 under a revised version of the Paragraph, which still made sexual relations between men up to the age of 21 illegal. In 2002 the German government issued an official apology to the LGBT community.

In the 1970s, the pink triangle was revived as a symbol of protest against homophobia. Publications promoted the pink triangle as a memorial to those who had been persecuted.

In the 1980s, the pink triangle was increasingly used not just as a memorial but as a positive symbol of both self and community identity. It commonly represented both gay and lesbian identity, and was incorporated into the logos of such organizations and businesses. It was also used by individuals, sometimes discretely or ambiguously as an “insider” code unfamiliar to the general public. The logo for the 1987 March on Washington for Lesbian and Gay Rights was a silhouette of the US Capitol Dome superimposed over a pink triangle.

Taking a more militant tone, the AIDS Coalition To Unleash Power (ACT UP) adopted an upward-pointing pink triangle on a black field along with the slogan “SILENCE = DEATH” as its logo. This organization was formed to draw attention to the disease’s disproportionate impact on gay and bisexual men, and the apparent role of “genocidal” homophobia in slowing progress on medical research. Some use the triangle in this orientation as a specific “reversal” of its usage by the Nazis.

The Pink Panthers Movement in Denver, Colorado adopted a pink triangle with clawed panther print logo, adapted from the original Pink Panthers Patrol in New York City.

In the 1990s, a pink triangle enclosed in a green circle came to be commonly used as a symbol identifying “safe spaces” for LGBT people at work or in school.

The pink triangle served as the basis for the “biangles”, a symbol of bisexual identity which consists of pink and blue triangles overlapping in a lavender or purple area. The pink and blue symbolize either homosexuality and heterosexuality, or female and male gender, reflecting bisexuals’ attraction to both.