Courier
From Memory Alpha, the free Star Trek reference
In general, a courier is an individual who serves as a messenger for various important deliveries.
Klaang was a courier on a mission for the Klingon High Command in 2151 when his scoutship crashed on Earth. (ENT: "Broken Bow")
Morn was given the task of being the courier that delivered a message to Starfleet that the Dominion was about to bring down the minefield blocking the Bajoran wormhole. (DS9: "Favor the Bold")
In starship classification, a courier vessel functions in a similar capacity, often rendezvousing with other ships in deep space or at space stations.
The USS Hera was on a routine courier mission when it disappeared in 2370. (TNG: "Interface")
The Maquis utilized modified support couriers in their attacks on the Cardassians in the DMZ. (DS9: "The Maquis, Part I")
In 2371 Rom requested that a special relief shipment he ordered on behalf of Zek be sent by high warp courier. (DS9: "Prophet Motive")
