Rabbi Samuel ben Moses de Medina (abbreviated RaShDaM, Hebrew: רשד"ם or Maharashdam; 1505 – October 12, 1589), was a Talmudist and author from Thessaloniki.
He was principal of the Talmudic college of that city, which produced a great number of prominent scholars during the 16th and 17th centuries.
While on a mission to Constantinople he met the noted grammarian Menahem Lonzano, who studied under him for some time and who therefore speaks of him as his teacher (David Conforte, Kore ha-Dorot, ed.
Among Samuel's many disciples who attained prominence were Abraham de Boton, Joseph ibn Ezra and Ḥayyim Shabbethai.
He had a controversy with Joseph Karo and other rabbis at Safed, against whom he wrote a polemical letter (Ketav Tochachah).