Rabban Gamliel the Elder רבן גמליאל הזקן

He worked while the Temple still stood, at the head of the Sanhedrin. His enactments in Mishnah Gittin come under the general formula mipnei tikkun ha-olam — for the good order of the world: a husband may not annul a bill of divorce behind his wife's back; all the parties' names must be written out in the document so there is no confusion; a widow receives her ketubah on oath.

All three are visibly about one thing: that the legal system work predictably and that the weaker party not be left defenceless.

A common confusion is worth naming here. The prozbul — the device that lets a debt survive the seventh year — is not his enactment but his grandfather Hillel's. In Mishnah Gittin the prozbul stands nearby, in the same chapter and under the same formula, and the proximity keeps getting the two mixed up.

Mishnah Sotah lists the losses generation by generation, and of him it says: "when Rabban Gamliel the Elder died, the honour of the Torah ceased, and purity and abstinence died."