Ux-Mal

From Memory Alpha, the free Star Trek reference

Ux-Mal is an inhabited star system. In the 19th century, a number of criminals from Ux-Mal were exiled to a moon of Mab-Bu VI. Their consciousness was separated from their bodies, and left adrift to suffer in the moon's intense electromagnetic storms.

When the USS Enterprise-D attempted to identify the source of the distress call from Mab-Bu VI, the criminal entities took over the minds of Data, Troi, and Miles O'Brien.(TNG: "Power Play")

Troi and Data taken over by Ux-Mal criminals.

Troi and O'Brien struck by the plasma shock

Hundreds of condemned prisoners from Ux-Mal.