Eli

From Memory Alpha, the free Star Trek reference.

Eli was a therapist at the Tantalus Penal Colony in 2266. He operated the neural neutralizer at least part of the time, and conditioned patients with it in the same manner Dr. Tristan Adams did. Eli possessed the same sort of vague, blank look a lot of the Tantalus staff possessed. (TOS: "Dagger of the Mind")

Eli was portrayed by Eli Behar. He was credited as 'Therapist', but in one scene, Tristan Adams called him Eli.