| Rebbe of Bobov-45 | |
| Began: | March 23, 2005 |
| Ended: | Current |
| Nationality: | American |
| Birth Name: | Mordechai Dovid Unger |
| Main Work: | Sheira D'bei Rav |
| Spouse: | Rivka Halberstam |
| Children: | Yosef, Shulim, Chaim Benzion, Yechezkel, Moshe Yehoshea |
| Father: | Yaakov Yitzchok Unger |
| Birth Place: | New York |
Mordechai Dovid Unger (Hebrew: הרב מרדכי דוד אונגער, born 1954) is the first Rebbe of Bobov-45.
Unger was born to Yaakov Yitzchok Unger of Dombrov.[1] He is the younger son-in-law of Naftali Zvi Halberstam, the fourth Bobover Rebbe.
Following the death of his father-in-law right before the Purim holiday in 2005,[2] a dispute arose as to who should be the Grand Rebbe of the then 120,000 Bobov Hasidim worldwide. Some began to follow Ben Zion Aryeh Leibish Halberstam, his father-in-law's half-brother, while others followed the older (by one year) Unger, who had by then already ensconced himself firmly within the community. Unger could not challenge his own father for leadership of Dombrov, which anyway was not as substantial a dynasty as Bobov. The matter of succession was brought before a beth din (religious court) in 2007, which ruled that Halberstam would be declared Rebbe of Bobov (Hebrew: אדמו"ר מבאבוב) with its headquarters on 48th Street in Borough Park, Brooklyn, while Unger would be Rebbe of Bobov-45 (Hebrew: אדמו"ר מבאבוב-45), located on 45th Street.[3]
Brooklyn Borough President Eric Adams visited Bobov–45 as part of his 2017 re-election campaign.[4]