The Poseidon missile was the second US Navy ballistic missile system, powered by a two-stage solid fuel rocket. It succeeded the Polaris missile beginning in 1972, bringing major advances in warheads and accuracy. It was followed by Trident I in 1979, and Trident II in 1990.

Poseidon, although longer and considerably heavier than Polaris A-3, had the same 4600 km (2500 nautical mile) range. It also had improved accuracy and up to 14 W68 multiple independently targetable reentry vehicles (MIRV) in its warhead bus.

See also: List of missiles