Izrael Kalmanowicz Poznanski (b. 1833 in Aleksandrów; d. 1900 in Lodz, Poland) was a textile magnate and philanthropist in Lodz, and the husband of Elenora Hertz Poznanski.

One of the most eminent entrepreneurs in the Russian-dominated part of Poland, Poznanski was the son of a Jewish merchant of Kowal, who built up a textile empire and became, next to Karl/Karol Scheibler, the most important manufacturer of Lódz, a 'multicultural' city mainly populated by Poles (Catholic and Jewish) and Germans. The bourgeoisie of these groups was described in Reymont's novel about Lodz The Promised Land (Ziemia Obiecana), later filmed by Andrzej Wajda.

Since 1989, the city of Lodz has rediscovered its industrial heritage, a unique ensemble of architecture, preserved despite two World Wars. The sites linked to Poznanski's memory are among the most prominent of the city: the huge factory buildings in Ogrodowa Street; the nearby Poznanski Palace, today a museum (including an exhibition about Arthur Rubinstein, another 'Lodschermensch'); and Poznanski's marble tomb in the Jewish cemetery, the biggest Israelite graveyard in Europe. Although Poznanski was devout to the belief of his ancestors, it must be noted that the generous style of his grave monument is scarcely compatible with Jewish tradition, as that religion forbids any luxury for funerals and tombs. (From Findagrave - copied by the author.)

The mausoleum of Izrael and Eleonora Hertz Poznanski is probably the largest Jewish tombstone in the world. The mausoleum and mosaic covering the inside of the dome were restored in 1993.