The Fairy Queen or Queen of the Fairies was a figure from folklore who was believed to rule the fairies. Based on Shakespeare's influence, in English-speaking cultures she is often named Titania or Mab.
Fairy Queen Wikipedia
In Irish folklore, the last High Queen of the Daoine Sidhe - and wife of the High King Finvarra - was named Una (or Oonagh, or Oona, or Uonaidh etc.). In the ballad tradition of Northern England and Lowland Scotland, she was called the Queen of Elphame.
The character is also associated with the name Morgan (as with the Arthurian character of Morgan Le Fey, or Morgan of the Fairies), Maeve, and L'annawnshee (literally, Underworld Fairy). In the Child Ballads Tam Lin (Child 39) and Thomas the Rhymer (Child 37), she is represented as both beautiful and seductive, and also as terrible and deadly. The Fairy Queen is said to pay a tithe to Hell every seven years, and her mortal lovers often provide this sacrifice. In Tam Lin, the title character tells his mortal lover:
At the end of seven years
She pays a tithe to Hell
I so fair and full of flesh
I fear it be myself
Both Edmund Spenser and William Shakespeare used folklore concerning the Fairy Queen to create characters and poetry, Spenser in The Faerie Queene and Shakespeare most notably in A Midsummer Night's Dream. In The Faerie Queene, Spenser's fairy queen is named Gloriana, and is also referred to as Tanaquill, which "appears to be an epithet for Gloriana, Queen of Faeries" derived from the name of the wife of Tarquinius Priscus. She is the daughter of Oberon, who in Shakespeare's later play is married to Titania, a name derived from Ovid as an epithet of the Roman goddess Diana. Diana was regularly portrayed as the ruler of the fairy kingdom in demonological literature, such as King James VI of Scotland's Daemonologie, which says that she belongs to "the fourth kind of spirits, which by the Gentiles [non-Jews] was called Diana and her wandering court, and amongst us is called Fairy (as I told you) or our good neighbours".
In one of the earliest of the Peter Pan novels, The Little White Bird, author J.M. Barrie also identifies Queen Mab as the name of the fairy queen, although the character is entirely benign and helpful. In Disney's series of films based on Tinker Bell, a fairy character originating in Barrie's novels, the fairies are shown to be ruled by a Queen Clarion. In Brandon Mull's Fablehaven series, the Fairy Queen is an essential part of the plot making key characters extremely powerful. The character Erza Scarlet from Hiro Mashima's Fairy Tail rightfully earned the alias "Titania" due to her overwhelming power being well known throughout the series' fictional land of Fiore.
The concept of a Dianic queen of spirits influenced the neopagan cultures developed from Charles Godfrey Leland's concept of Aradia "Queen of the Witches". The Faerie faith developed from the same source as the McFarland Dianic tradition.