Almost all the Gedolim speak Yiddish, including:
Rav Aharon Leib Shteinman
Rav Yosef Shalom Eliashev
Ponevezh Roshei Yeshiva
Gerrer Rebbe
Belzer Rebbe
Klausenberger Rebbe
Rav Shmuel Auerbach
Rav Meir Tzvi Bergman
Rav Nissim Karelitz
Rav Yitzchok Sheiner
Rav Yitzchak Zilberstien
etc etc