A fetterlock is a sort of shackle that is a common charge in heraldry, often displayed in a way that resembles a padlock.

King Edward IV used a heraldic badge consisting of a fetterlock and a falcon. This was originally the badge of the first Duke of York, Edmund Langley, who used the falcon of the Plantagenets in a golden fetterlock. This was also used by his grandson Richard of York, who displayed the fetterlock opened.^[1]

Fetterlocks feature in the crests of the Wyndham family of Norfolk, the Long family of Wiltshire and Clan Grierson of the Scottish Lowlands.