The inverted black triangle (German: schwarzer Winkel) was an identification badge used in Nazi concentration camps to mark prisoners designated asozial  [de] ("a(nti-)social") and arbeitsscheu ("work-shy"). The Roma and Sinti people were considered asocial and tagged with the black triangle. The designation also included disabled individuals, alcoholics, beggars, homeless people, nomads, and prostitutes (though male sex workers were marked with the pink triangle), as well as violators of laws prohibiting sexual relations between Aryans and Jews. Women also deemed to be anti-social included lesbians and others deemed as nonconformists.

The symbol originates from Nazi Germany, where every prisoner had to wear a concentration camp badge on their prison clothes, of which the design and color categorized them according to the reason for their internment. The homeless were included, as were disabled people, alcoholics, those who habitually avoided labor and employment, draft evaders, pacifists, Roma and Sinti people, and others.

Romani first wore the black triangle with a Z notation (for Zigeuner, 'gypsy') to the right of the triangle's point. Male Romani were later assigned a brown triangle. Female Romani were still deemed asocials as they were stereotyped as petty criminals (prostitutes, kidnappers and fortune tellers).

The Nazis marked disabled concentration camp inmates with a black triangle. Some United Kingdom-based groups concerned with the rights of disabled people have adopted the symbol in their campaigns, citing press coverage and government policies - including changes to disability benefits and Disability Living Allowance, as the reasons for their campaigns. "The Black Triangle List" was created to keep track of welfare-related deaths due to cuts by the Department for Work and Pensions.