International audience Seven centuries before the discovery of the African zebras by the Europeans, the names zebro andzebra were given to an enigmatic equid widely reported in the Iberian Peninsula during the MiddleAges. Roughly 150 toponyms deriving from the words zebro/a have been recorded in Iberia startingfrom the IXth century A.D. together with 65 Portuguese Forais and 16 Spanish Fueros (i.e. town laws)referred to these animals as onagri or zebros – Latin and Romance etimology respectively – duringthe XIIth and XIIIth centuries. However, the precise biological nature of the animal remains unclearto this day. Four hypotheses have been put forward to explain the taxonomic status of the zebro:1) Equus hydruntinus, an extinct onager; 2) the antecessor of the Sorraia horse breed; 3) a modernonager species introduced by the Muslims; and 4) a feral domestic equid, either an ass or a horse. Thispaper addresses the issue by reviewing the historical and nomenclatural data on the subject, whilebriefly covering the genetic and archaeozoological evidence that may eventually shed light on the issue.