Rabbi Yonasan Steif (Yiddish: יונתן שטייף; August 12, 1877 – August 25, 1958) was a senior dayan of Budapest, Hungary, before the Second World War, a man whom Rabbis Moshe Feinstein and Joel Teitelbaum referred to as the gadol hador (spiritual leader of the generation).
While Rabbi Steif may have assumed the role of rosh beth din as the year 1944 approached, he was not such for most of his tenure.
Rabbi Steif was rescued from death in the Holocaust in 1944 as a result of a deal between Rudolph Kastner, and a deputy of Adolf Eichmann.
He journeyed on the Kastner train, a special train bound for neutral Switzerland, along with other prominent Jews including the Satmar Rebbe, Rabbi Joel Teitelbaum; the Debreciner Rov, Rabbi Moshe Stern; Adolph Deutsch, head of the Budapest branch of Agudath Israel; and many "ordinary" Jews.
His son-in-law Aron Bleier (Esther's husband) was in the concentration camps at the time but miraculously survived and was re-united with the family after the war.