A Tilonian who appears in different guises in Commander Riker's disordered mind in 2369 and is in reality one of those interrogating him.
Suna appears in the episode Frame of Mind, played by Andrew Prine.
Riker first notices him as an unfamiliar lieutenant aboard the Enterprise-D, an alien officer who seems to be watching him during rehearsals for Doctor Crusher's play. When Riker's surroundings change to an asylum on Tilonus IV, the same man is there as the administrator who will decide what is to be done with him.
The repeated face is a clue. Riker has been seized while working undercover on Tilonus IV, a world in turmoil after its government fell. His captors are using a device on his brain to pull out what he knows. Suna is one of them, and Riker's mind has woven him into every false setting. Riker breaks through the illusions, wakes on a table and escapes.