|Issamar of Nadvorna|
| Grand Rabbi Isamar Rosenbaum "The Elder"|
|Term||1902 – 1973|
|Full name||Issamar Rosenbaum|
|Buried||Mount of Olives|
Rabbi Isamar Rosenbaum (1886-1973) was a Hasidic rebbe, and the progenitor of the extended Hasidic dynasty of Nadvorna and Kretshniff. He was the son of Rabbi Meyer Rosenbaum of Kretshniff, who in turn was a son of Rabbi Mordechai of Nadvorna.
Isamar Rosenbaum became a rebbe at the age of sixteen and, at his father's behest, moved to Czernowitz where he served as a chasidic rebbe. In the Nadvorna dynasty, all children of the rebbes open their own chasidic courts, even during their fathers' lifetime. His wife, Rebbitzen Malka, was the daughter of Rebbe Usher Yeshaya Rubin of Kolbuszowa, Galicia.
His family was the only chasidic family of grand rabbis known to have all survived the Nazi camps with the whole family intact.
In 1969 (20 Marcheshvon 5730), Rebbetzen Malka died; she was brought to Tveria for burial.
At the time of his death, he was one of the longest living chassidic rebbes in history; he was known as the Admor Hazaken miNadvorna, or "Elder Rebbe of Nadvorna".
He died at the age of 86 in 1973 (Sivan 5733) and laid to rest in the Mount of Olives.
All his sons and sons-in-law, were chasidic rebbes, with the sole exception of his son Rabbi Meyer Rosenbaum, who was the Chief Rabbi of Cuba, and a prolific author of scholarly works, including Torah LeOhr Hatekufah.
Rabbi Meyer Rosenbaum of Kretchniff
|Rebbe of Nadvorna|
| Succeeded by|
Grand Rabbi Chaim Mordchai of Nadvorna
Grand Rabbi Yisochor Ber of Strozhnitz
Grand Rabbi Yitzchak Isaac of Zutshka
'Grand Rabbi Usher Yeshaya of Nadvorna-Chadera