The beloved of Amadis of Gaul, who called himself Beltenebros when he retired to the Poor Rock. (Amadis de Gaul, ii. 6.)
Queen Elizabeth is sometimes called the “peerless Oriana,” especially in the madrigals entitled the Triumphs of Oriana (1601).
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894