The Vampire dugout (known locally in Belgium as the Vampyr dugout), is a First World War underground shelter located near the Belgian village of Zonnebeke. It was created as a British brigade headquarters in early 1918 by the 171st Tunnelling Company of the Royal Engineers after the Third Battle of Ypres/Battle of Passchendaele.

Rediscovered in 2007, the Vampire dugout was the subject of a 2008 British television programme (Time Team) which was also broadcast abroad. The structure is inaccessible to the public, but inspected regularly by battlefield historians.

At the end of the Battle of Passchendaele, having expanded the Ypres Salient by retaking Passendale Ridge, the British were left with little natural shelter from the former woods and farms. The artillery of both sides had flattened the landscape. As the static nature of the conflict gave way to a more mobile war, and the opposing sides developed better technology and tactics, particularly in artillery, the need arose to protect troops within deeper and deeper shelters close to the frontline. What started out as simple blast shelters turned over time into subterranean hospitals, mess rooms, chapels, kitchens, workshops, blacksmiths, as well as bedrooms where exhausted soldiers could rest.

Needing shelter for their troops on Passendale Ridge, the Allied High Command in January 1918 moved 25,000 specialist tunnellers of the Royal Engineers and 50,000 attached infantry to the north-east of Ypres. Most of the men involved had prepared and taken part in the Battle of Messines (7–14 June 1917), where they had dug 26 deep mines as well as nearly 200 individual shelter structures at depths of 30 m (98 ft) into the local blue clay. These underground barracks built by the Royal Engineers could accommodate units from 50 men up to 2,000 as in the largest dugouts at Wieltje and Hill 63. Connected by corridors measuring 6 ft 6 in (2.0 m) high by 4 ft (1.2 m) wide, the deep dugouts were fitted with water pumps to deal with the high groundwater tables in the area. The level of these World War I underground activities can be gauged by the fact that by March 1918, more people lived beneath the surface in the Ypres area than reside above ground in the town today.

Vampire was built to house a brigade headquarters of up to 50 men and one senior commanding officer. Located close to Polygon Wood, it was named after the supply soldiers whose mission was to come out at night to resupply troops in the front line. Located 14 m (46 ft) below Flanders and dug over a period of four months by 171st Tunnelling Company, the Royal Engineers used I beams and reclaimed railway line in a D-type sett structure. This was then further reinforced using stepped wooden horizontal beams.

Vampire became operational from early April 1918, first housing the 100th Brigade of the British 33rd Division, then the 16th King's Royal Rifle Corps and then the 9th Battalion Highland Light Infantry Regiment. But after only a few weeks, the dugout was lost when the Germans undertook the Battle of the Lys in April 1918. It was recaptured in September 1918, when its last occupants became the 2nd Battalion of the Worcestershire Regiment.

When Vampire was excavated in 2008 (see below), the archaeologists found many signs inside the dugout of occupation by the British, but few from the Germans. There was a total absence of metal bed structures, suggesting that the British had had little time to fit out the dugout before it was overrun. The researchers first estimated that the dugout would measure 200 m (660 ft) by 150 m (490 ft), but tunnels were eventually found to cover an area of 800 m (2,600 ft) by 600 m (2,000 ft). Designed by the Royal Engineers to house 50 men, the researchers now estimate that Vampire may have been used by at least 300 soldiers. Whether Vampire was extended by the British or the Germans will take further investigation, although signs of construction in progress have been found throughout the workings.

These three battalions were the three constituent battalions of 100 Brigade