Navis actuaria

thumb|Reproduction of a 3rd century depiction of an actuaria from the Altiburus mosaic. The figure towards the bow of the ship is beating the time for the rowers with a mallet. An actuaria (plural: actuariae; a short form of navis actuaria, "ship that moves") was a type of merchant galley used primarily for trade and transport throughout the Roman Empire. In Greek, they were also known by the term akatos (ἄκατος; plural: akatoi). The actuaria was equipped with sails as well as oars.

Variants of the actuaria were used as troop transports, for example in the invasion of Britain. In 47 BC, Publius Vatinius equipped actuariae at Brindisi with temporary rams to support Julius Caesar's forces in Illyricum, on the other side of the Adriatic, though these were only suitable to combat smaller enemy vessels. Actuariae were also employed along the major rivers by Germanicus in his campaigns against the Germanic tribes around 16 AD.