World War I memorials commemorate the events and the casualties of World War I. These war memorials include civic memorials, larger national monuments, war cemeteries, private memorials and a range of utilitarian designs such as halls and parks, dedicated to remembering those involved in the conflict. Huge numbers of memorials were built in the 1920s and 1930s, with around 176,000 erected in France alone. This was a new social phenomenon and marked a major cultural shift in how nations commemorated conflicts. Interest in World War I and its memorials faded after World War II, and did not increase again until the 1980s and 1990s, which saw the renovation of many existing memorials and the opening of new sites. Visitor numbers at many memorials increased significantly, while major national and civic memorials continue to be used for annual ceremonies remembering the war.

Architecturally, most war memorials were relatively conservative in design, aiming to use established styles to produce a tragic but comforting, noble and enduring commemoration of the war dead. Classical themes were particularly common, taking the prevailing styles of the late 19th century and typically simplifying them to produce cleaner, more abstract memorials. Allegorical and symbolic features, frequently drawing on Christian imagery, were used to communicate themes of self-sacrifice, victory and death. Some memorials adopted a medievalist theme instead, looking backwards to a more secure past, while others used emerging realist and Art Deco architectural styles to communicate the themes of the war.

The commissioning of memorials occurred through a wide range of national and local institutions, reflecting local political traditions; funding was similarly disparate, with most countries relying heavily on local charitable contributions to cover the costs of construction. War cemeteries and memorials to particularly significant battles, however, were typically centrally controlled and funded by the state. The war encouraged the creation of new forms of memorial. Lists of memorial names, reflecting the huge scale of the losses, were a common feature, while Tombs of the Unknown Soldier containing a selected, unidentified body, and empty cenotaph monuments commemorated the numerous unidentifiable corpses and those servicemen whose bodies were never found. Ceremonies were often held at the memorials, including those on Armistice Day, Anzac Day and the Fêtes de la Victoire, while pilgrimages to the sites of the conflict and the memorials there were common in the inter-war years.