The Romani Holocaust or the Romani genocide was the planned effort by Nazi Germany and its World War II allies and collaborators to commit ethnic cleansing and eventually genocide against European Roma and Sinti peoples during the Holocaust era.

In World War II, many governments, organizations and individuals collaborated with the Axis powers, "out of conviction, desperation, or under coercion." Nationalists sometimes welcomed German or Italian troops they believed would liberate their countries from colonization. The Danish, Belgian and Vichy French governments attempted to appease and bargain with the invaders in hopes of mitigating harm to their citizens and economies.