Convoy PQ 18 was the last of the PQ/QP series of arctic convoys during World War II, bound from US and British ports via Reykjavík in Iceland to the Barents Sea and White Sea ports of the Soviet Union, particularly Murmansk and Archangel. The convoy sailed on 2 September 1942 and arrived three weeks later on 21 September 1942. It was opposed by German sea and air forces based in occupied Norway.