PLAYED BY: David Selburg
SPECIES: Tilonan Male

The psychiatrist character in a fiendish, brain-washing scenario prepared by interrogators on Tilonus IV trying to harvest tactical data from William Riker. Syrus worked at the Tilonus Institute for Mental Disorders.

PLAYED BY: Andrew Prine
SPECIES: Tilonan Male

Humanoid native of Tilonus IV who used a sophisticated mind-controlling apparatus on William Riker after his capture in 2369. Suna was determined to learn Riker's secrets, but did not.
 

PLAYED BY: Gary Werntz
SPECIES: Tilonan Male

Illusional being who tormented William Riker during the latter's cerebrally-induced incarceration in the Tilonius Institute for Mental Disorders, where Mavek served as an orderly.