A personnel carrier (or personnel transport, troop transport, etc.) is any starfaring vessel designed to transport military personnel to a specific destination, especially a battle zone.
Armaments on a personnel carrier may be as little as two phaser banks or may be a well-armed craft such as a Calgary-class heavy troop transport. (Star Fleet Data File, vol. 1) As well, transport/tugs such as those of the Ptolemy-class may attach specialized transport containers to serve as personnel carriers. (Star Fleet Technical Manual)