Marceli Landsberg (born 28 March 1890 in Tomaszów Mazowiecki, Poland – 25 June 1951 in Łódź, Poland), physician, specialist in internal medicine and contagious diseases, professor of the Medical Academy in Łódź.
The younger son of Alexander Landsberg (1859–1928), an industrialist from Tomaszów Mazowiecki, and his wife, Eleonora (1862–1942), Marceli married Maria Sachs, who bore him two daughters: Anna Haar (1921–1984) and Elizabeth Janina (b.
His grandfather, Hilary Landsberg (1834–1898), was a cloth manufacturer in Tomaszów Mazowiecki who was of Sephardi descent.
After receiving his graduation diploma in Odessa, he studied medicine in Berlin and Freiburg.
In 1913, he earned doctorate in medicine "magna cum laude" on the basis of his German dissertation entitled Studien zur Lehre von der Blutgerinnung.
From 1934 to 1939, he worked as a director of internal medicine in the Jewish hospital on Czysta Street in Warsaw.