Mister Suna was a Tilonian military officer who was a member of a faction who resorted to torture for information. This faction formed after the government splintered on Tilonus IV.

In 2369, after Commander William T. Riker was ambushed during a mission on the planet, Suna used a neurosomatic technique in an attempt at extracting strategic information from the Starfleet officer. In the delusions created by the technique, Suna appeared as a Starfleet science lieutenant aboard the USS Enterprise-D or as a hospital adminstrator at the Tilonus Institute for Mental Disorders. Recognizing that Suna was the only constant between the two places and that he was being lied to, Riker was able to return to consciousness and had himself beamed back to the USS Enterprise-D in an emergency beam-out. (TNG: "Frame of Mind")

Suna was played by Andrew Prine.
The first draft script gives his full name as Nigral Suna and describes him as a black market dealer in extracted memories.
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