The word Merlin may refer to:

• Merlin, the wizard, associated with King Arthur.
• Merlin is a television miniseries based on Arthurian legend.
• Merlin, the bird of prey.
• Merlin, the charity that provides an immediate and effective response to medical emergencies throughout the world.
• The Rolls-Royce Merlin engine for aircraft.
• The SpaceX Merlin engine for rockets.
• The Merlin military helicopter.
• The Order of Merlin is a fictional honour appearing in the Harry Potter series by J. K. Rowling.
• MERLIN is the Multi-Element Radio Linked Interferometer Network.
• Merlin is a Chattanooga, TN manufacturer of custom titanium bicycles.
• Asteroid 2598 Merlin is named after the wizard.
• Philippe-Antoine Merlin, member of the Executive Directory of the French Republic
• AT&T Merlin brand name of office telephones, now produced and marketed by Lucent.
• Merlin was a 'smart' anti-tank mortar round for the British 81 mm mortar. It was cancelled in the 1990's.

See also Merlyn