The Brotherhood of Blackheads is an association of local unmarried merchants, ship owners, and foreigners that was active in Livonia (present-day Estonia and Latvia) from the mid-14th century till 1940 but still remains active in present day Hamburg. The Brotherhood of Blackheads was founded as a military organization but the non-military aspects of the association gradually became more pronounced until the Brotherhood became a predominantly social organization after the end of the Great Northern War.