The remembrance poppy (a Papaver rhoeas) has been used since 1921 to commemorate military personnel who have died in war. Inspired by the World War I poem "In Flanders Fields", and promoted by Moina Michael, they were first adopted by the American Legion to commemorate American soldiers killed in that war (1914–1918). They were then adopted by military veterans' groups in parts of the former British Empire: the United Kingdom, Canada, Australia and New Zealand. Today, they are most common in the UK and Canada, and are used to commemorate their servicemen and women killed in all conflicts since 1914. There, small artificial poppies are often worn on clothing leading up to Remembrance Day/Armistice Day (11 November). Poppy wreaths are also often laid at war memorials.

The remembrance poppy is especially prominent in the UK. In the weeks leading up to Remembrance Sunday, they are distributed by The Royal British Legion in return for donations to their "Poppy Appeal", which supports all current and former British military personnel. During this time, all public figures and people appearing on television are expected to wear them, and those who do not have been criticized. Some have berated this as "poppy fascism" and argued that the Appeal is being used to justify and glorify current wars. In Northern Ireland the poppy is especially controversial and politicized; most Irish nationalists and Irish Catholics refuse to wear one, mainly due to actions of the British Army during the Troubles, while Ulster Protestants and Unionists usually wear them.