Ben Bag-Bag was a Rabbi and a disciple of Rabbi Hillel of the early Tannaim age, appearing at the end of the Mishnah in Pirkei Avot. He is quoted by the Mishna, Turn it, and turn it, for everything is in it. Reflect on it and grow old and gray with it. Don't turn from it, for nothing is better than it. Another mysterious Rabbi of the same time, by the name of Ben He-He, is considered by some to be the same person.
Speculation by Torah scholars leads many to believe these names to be labels to cover the true identities of these Rabbis because they were gerim who were persecuted by Roman authorities during the Roman occupation of the Land of Israel. Another Rabbinic tradition holds that Ben Bag Bag was a Jewish convert that Hillel symbolically taught the whole Torah while he stood on one foot.
Some would also identify Ben Bag-Bag with Johanan ben Bag-Bag (Hebrew: יוחנן בן בג בג). a tanna mentioned several times in the Talmud.