I don't have any famous rabbis in my family history, at least not that I know of. But I once found some sort of connection -- a world-famous rabbi who was the maggid of my paternal grandparents' town in Poland (over a hundred years before they were born). One of the leading antagonists of Chassidim in the late eighteenth century was R. David Makover. He was the author of the anti-Chassidic tracts Zemer Aritzim and Shever Poshim (see vol. 2 of Mordechai Willenski's Chassidim U-Misnagdim).
R. David ben Benzion Yechezkel was the maggid (preacher) in the town of Makov, hence his title R. David Makover. My grandparents came from a town named Makow Masovietski. I assumed that this was the same Makov as R. David's and some historically-minded friends agreed with me bu one dissented. I recently asked Prof. Shaul Stampfer about this and he responded that in Pinkas HaKehilot - Polin, vol. 4 p. 265 it says that R. David the author of Zemer Aritzim was from Makow Masovietski.
I remember hearing that Chassidic legend has it that as punishment for R. David Makover's anti-Chassidic attitude, the entire town became Chassidic. However, I was reading Me-Rachok Kokhav Menatznetz, the recently published memoirs of Mordechai Ciechanower, a survivor from Makow (and a distant cousin of mine), and he writes about the different shuls from his youth: There were two batei midrash and shtiblakh for Gerrer Chassidim, Amshinover Chassidim and Alexander Chassidim. He writes that he used to attend the Misnaged beis midrash with his father.