Kalonymos or Kalonymus (Hebrew: קלונימוס) is a prominent Jewish family who lived in Italy, which, after the settlement at Mainz and Speyer of several of its members, took during many generations a leading part in the development of Jewish learning in Germany. The family is according to many considered the foundation of Hachmei and Hasidei Ashkenaz.
The name ought really to be spelled "Kalonymos," as Kalonymus ben Kalonymus and Immanuel of Rome both rhyme it with words ending in "-mos". The name, which occurs in Greece, Italy, and Provence, is of Greek origin; Kalonymos (Kαλώνυμος) stands for "good name" in Greek and Wolf correctly pointed that it is a translation of the Hebrew "Shem-Tob"; Zunz, that it represented the Latin "Cleonymus".
Traces of the family in Italy may be found as early as the second half of the eighth century. As to the date of the settlement of its members in Germany, the opinions of modern scholars are divided, owing to the conflicting statements of the Jewish sources.
Rapoport, Leopold Zunz, and many others place the settlement in 876, believing the King Charles, mentioned in the sources as having induced the Kalonymides to emigrate to Germany, to have been Charles the Bald, who was in Italy in that year; Luzzatto and others think that it took place under Charlemagne, alleging that the desire to attract scholars to the empire was more in keeping with the character of that monarch; still others assign it to the reign of Otto II (973-983), whose life, according to the historian Thietmar von Merseburg, was saved in a battle with the Saracens by a Jew named Kalonymus. The following table, compiled from the accounts of Eleazar of Worms and Solomon Luria, gives the Italian and German heads of the family, which produced for nearly five centuries the most notable scholars of Germany and northern France, such as Samuel he-Hasid and his son Judah he-Hasid. Although all of them are mentioned as having been important scholars, the nature of the activity of only a few of them is known.