Q

The common name for (presumably) multiple members of the 'Q Continuum'. Several people have encountered Q: former Orion Union president Ventil Oyana, who encountered a Q who presented herself as an Orion Empress and sought to judge Oyana and her people; Captains Michel Thuir and Langa Mbeki, who encountered a Q who presented herself as a judge of humanity, and who followed Thuir to Starfleet Academy; and Captain Iliae Rurliss, who encountered a Q who initially presented himself in the guise of Riala before, again, seeking to judge a people, in his case the Amarki.

There's a pattern, you see.