An Orion vessel was a type of vessel used by Orion pirates, a design that had not yet been encountered by the Federation in 2270, but which could be identified by its Orion markings.
This type of Orion vessel was armed with standard phasers, described as weak with a diffused, low-quality beam, and could neither outrun or outgun a Constitution-class starship, but was powerful enough to overtake a Huron-type freighter. This type of vessel also emitted a unique trail of radioactive waste that was visible on a spectral analysis.
In 2270, an Orion vessel attacked the USS Huron for its cargo of dilithium crystals, as well as a special supply of strobolin. It was later encountered by the USS Enterprise in a field of asteroids, where it was eventually surrendered and was towed to Deneb V. (TAS: "The Pirates of Orion")