The sources and fluxes of superGZK neutrinos, E>1020 eV, are discussed.
The most promising sources are reionization bright phase, topological defects,
superheavy dark matter and mirror matter. The energy of neutrinos can be above
the GUT scale (∼1016 GeV). The predicted fluxes are observable by
future space detectors EUSO and OWL.Comment: JD talk at XXI Texas Symposium (Florence