Variations: Iditxu, Iritxu
Ieltxu is a Basque creature found in the caverns and wells of Gernika. Notable haunts include a pit in Nabarrizmendi and the Busturia well.
Ieltxu appears either as a human or as a bird shooting flames from its mouth. At night only its burning fire is seen. While its appearances are sudden and terrifying, an ieltxu is not evil, merely mischievous. It enjoys leading people astray and getting them lost, especially if they can get lost near a cliff.
Around Bermeo it is Iditxu or Iritxu who appears as a small pig. It leads people on a merry chase through the night only to return them to where they started, exhausted and empty-handed.
References
Altuna, J.; Fornoff, F. H., White, L., and Evans-Corrales, C. trans. (2007) Selected Writings of Jose Miguel de Barandiaran: Basque Prehistory and Ethnography. Center for Basque Studies, Reno.