A reptilian shape-changing species with long prehensile tongues, one of whom posed as a human officer aboard the USS Quito and devoured a friend of Beckett Mariner.
Harvongians can take the form of other humanoids. Their true shape is a green-skinned reptile with clawed forearms, a second small pair of arms on the torso, a fanged snout and three tongues more than two metres long. They can shrug off several hand phaser hits.
The species appears in a flashback in the Lower Decks episode Cupid's Errant Arrow. During Mariner's service aboard the USS Quito, a Harvongian had taken the place of a crewman named Niko. It shed its disguise and swallowed his girlfriend Angie in front of Mariner.
The memory explains her behaviour years later on the USS Cerritos, where she is convinced that Brad Boimler's girlfriend, Barbara Brinson, must be some kind of impostor or parasite and sets out to prove it.