Q

A member of the Q Continuum. Omnipotent, omniscient, never really that helpful.

USS Nightingale
While on a mission to apprehend Dr. Helena Telafaro, the Nightingale made contact with this Q. It went less than smoothly, and while the ship was able to escape with Dr. Telafaro relatively unscathed there were consequences.

Ensign Jaime Ramerez, former head of security, was turned into a toddler and has yet to regain his original form.