General Contact Units (GCUs) are fast, independent, general-purpose vessels which the Culture's Contact? group uses for diplomacy, espionage, subversion and sabotage. The Culture has no policy of non-interference (such as the Prime Directive in the Star Trek series?) and, to the contrary, often tries to change the course of civilisations of whose behaviour it disapproves or which it considers in need of advancement.
GCUs typically have a crew of Contact members, numbering around 300. GCUs' Minds are sometimes somewhat eccentric (not to be confused with Eccentric–see below).
In the early stages of a conflict, GCUs are able to act as warships until GOU and ROU types become available. Because the Culture is more advanced than most other spacefaring civilisations, GCUs are usually very effective in combat. However during the Idiran-Culture War the Culture started to produce GOUs and ROUs which are optimised for combat.
Classes of GCU are usually named after geographical features. Some of the known classes are:
Troubadour Class (historical)
GCUs are much smaller than GSVs (though small only by comparison), and are routinely carried within GSVs on long journeys.
One of the best known GCUs in Banks' stories is Grey Area, known widely by the other Minds as Meatfucker because it breaches the taboo against looking inside the minds of living creatures.