Queen Mab, the supreme monarch of the Unseelie court of the Sidhe, or high fae, addresses the court.

From what I've found anything earlier doesn't have unseelie fay, this seems to be a later creation by Christian authors to try to convince people that some fairies were evil.

Earlier myths describe them as unpredictable, sometimes violent, but not bound to a court unless they were riding a hunt with a fairy queen or lord.

The evidence seems to imply that we created the idea of seelie vs unseelie fay.