The Morrígan

The courts of faerie are as iconic as they are inscrutable. Among their number count most of the myths, legends, and fairy tales of the mortal world, and few are better known than the queen sometimes called the triple goddess. The Morrígan is both a name and a title, borne by multiple beings who serve as aspects of the Morrígan, which count among their number such figures as Macha, Badb Catha, Morgan le fay, Medb, and the Matres and Matronae.
Despite these and many other beings phsically existing they are all still the Morrígan and retain a singular memory and identity. In this way stories from the distant past of those who've interacted with the Morrígan tie directly to present-day interactions with her and she recalls with perfect accuracy all events from her past, and some claim her future as well.
The Morrígan holds herself as a goddess of faerie and claims mastery over war, death, and fate. Their power is certainly unchallenged by other powerful fae lending legitimacy to her claims.