Rabban Gamliel of Yavne רבן גמליאל דיבנה
Nasi at Yavne, who fixed the liturgy and unified halakhah after the Destruction
He inherited the leadership from Rabban Yochanan ben Zakkai — and inherited a world that had to be rebuilt. The Temple was gone, communities were scattered, every place had its own custom. Rabban Gamliel understood that without one binding norm the people would dissolve into many peoples.
Hence his central acts. He completed the order of the weekday Amidah, the eighteen blessings that took the place of the daily offerings; in his time Shmuel HaKatan composed the added blessing against informers and sectarians. He shaped the Passover seder for a world without the paschal offering. And he insisted, sometimes harshly, that where the sages disagreed the law follows the majority.
The famous episode is his clash with Rabbi Yehoshua over the date of Yom Kippur: he ordered him to appear with staff and purse on the day Rabbi Yehoshua held to be the fast. Rabbi Yehoshua obeyed, and the Nasi met him with «peace to you, my teacher and my student».