The Corvallens were a hairless humanoid species with grey-brown crackled skin, pronounced cheekbones and a large chin. They were known to serve as mercenaries who often engaged in interstellar commerce. They were known to operate near the Romulan Star Empire and at least one Corvallen freighter visited Deep Space 9 in the 2370s. (TNG: "Face of the Enemy"; DS9: "Chimera")
In 2369, a Corvallen freighter was hired by members of the Romulan underground movement to transport Vice-Proconsul M'ret and his aides to the Federation so they could defect. However, when the freighter rendezvoused with the IRW Khazara, Deanna Troi (disguised as Major Rakal) sensed that the captain did not intend to complete his task. To protect the mission, Sub-Commander N'Vek destroyed the freighter. (TNG: "Face of the Enemy")
When the USS Enterprise-D contacted a Yridian freighter in the Ufandi system while searching for the Duras sisters, the Yridian captain claimed he had acquired the magnesite, which had been sold to him by the sisters, from a Corvallen. (TNG: "Firstborn")
- ENT: "Broken Bow"
Following the initial appearance of Corvallens in "Face of the Enemy", they were regularly identified on call sheets by the production nickname with some variation of "Puzzle Piece Alien".