Mark XI or Mark 11 often refers to the 11th version of a product, frequently military hardware. "Mark", meaning "model" or "variant", can be abbreviated "Mk."
Mark XI or Mark 11 may refer to:
Military Mark 11 torpedo (1926), American surface combatant torpedo Mark XI torpedo (1934), British aircraft-delivered torpedo Hedgehog Mark 11, variant of the Hedgehog, a British anti-submarine spigot mortar weapon Supermarine Spitfire Mk XI (1942-1944), variant of the Supermarine Spitfire, a British photo reconnaissance aircraft Bristol Beaufighter Mk XIC, variant of the Bristol Beaufighter, a British Coastal Command long range heavy fighter Mark 11 missile launcher, a naval based missile launcher Mark 11 nuclear bomb (1956-1960), an American nuclear bomb United States Navy Mk 11 Mod 0 Sniper Weapon System, based on the SR-25
Other uses Mark 11 or Mark XI, the eleventh chapter of the Gospel of Mark in the New Testament of the Christian Bible Mortal Kombat 11, a 2019 fighting video game