The Unlocking Charm, also known as the Thief's Friend (Alohomora) is a charm that unlocks and opens doors and windows that are not protected by magic. It is also able to open doors locked by the Locking Spell (Colloportus).

Although it is unknown who invented it (the spell was created in Africa) it was brought to Britain and hence to the world in the 17th century by Eldon Elsrickle. He used it to terrorise London, stealing from homes of Muggles and wizards alike, until Blagdon Blay invented the  Anti-Alohomora Charm.