R. Johanan ben Zakkai (first century C.E.) was a tanna and the leading sage at the end of the Second Temple period and the years following the destruction of the Temple. R. Johanan ben Zakkai's personality and work are depicted in a blend of fact and legend, neither of which gives information concerning his family or place of origin. Like Moses and Hillel before and Akiva after him, Johanan is said to have lived 120 years, divided into three periods: "For 40 years he was in business, 40 years he studied, and 40 years he taught" (Sif. Deut. 357; RH 31b; Sanh. 41a). In the chain of the tradition of the Oral Law it is mentioned in general terms that he received the tradition from Hillel and Shammai (Avot 2:8). Other statements, however, refer to him only as the pupil of Hillel, although these too contain no direct evidence of any discussions between them. One baraita declares that Johanan was the least among Hillel's 80 pupils "and it was said of him that he did not leave unstudied the Bible and Mishnah, Gemara, halakhah, and aggadah, exegetical details of the Torah and of the Scribes, inferences a minori ad majus and analogies, calendrical computations and gematriot, the speech of the ministering angels, of spirits, and of palm-trees, fullers' parables and fox fables, and any matter great and small.

There is clear evidence that Johanan was the first sage to engage in mysticism, heading as he does a chain, as it were, of sages who engaged in the subject, given by Yose b. Judah of the latter half of the second century C.E. (Tosef., Hag. 2:2). The accounts of his occupation with mysticism are distinguished by a lofty style and an intense fervor but do not disclose the essence of the esoteric doctrines. With these are connected two of Johanan's statements, the one describing the entrance to Gehinnom (Suk. 32b) and the other the size of the world (Hag. 13a; and see Pes. 94 a–b). These were, it seems, taken from a collection of beraitot, stemming according to the amora Rabbah b. Meryon "from the school of R. Johanan b. Zakkai" (Er. 19a, and Rashi ad loc.). Johanan's wisdom and activities earned for him an authority and an influence that extended beyond the circle of his pupils. Nothing is clearly known of his attitude to the events that took place in Jerusalem during the tempestuous years preceding the destruction of the Second Temple.

Johanan ascribed the destruction of the Temple to Israel's failure to perform the will of God; but he was the witness of circumstances that led him to express the view that his people had been delivered "into the hands of a low people" (Ket. 66b), and under the influence of events even changed his attitude toward the charitable acts of the non-Jews. With the destruction of the Temple the atonement of sins was denied not to Israel but to those who had destroyed it. Nor was Johanan content merely with such expressions of consolation, but worked principally for the renewal of the nation's religious and national leadership by raising the prestige of the bet din at Jabneh. His regulations issued to this end at first met with the opposition of some contemporary sages. During the existence of the Temple the shofar was sounded on a New Year that fell on a Sabbath only in the Temple but not elsewhere in the country. "After the destruction of the Temple R. Johanan b. Zakkai ordained that the shofar be sounded [on a Sabbath] wherever there was a bet din" (RH 4:1; and see RH 29b). A moving account is given of his death: "When he fell ill, his disciples went to visit him. When R. Johanan b. Zakkai saw them, he began to weep. His disciples said to him: 'Light of Israel, pillar of the right hand, mighty hammer! Why do you weep?' He replied: 'If I were being taken today before a human king who is here today and tomorrow in the grave, whose anger - if he is angry with me - does not last for ever, who if he imprisons me does not imprison me for ever, and who if he puts me to death does not put me to everlasting death, and whom I can persuade with words and bribe with money, even so I would weep. Now that I am being taken before the supreme King of Kings, who lives and endures for ever and ever, whose anger is an everlasting anger, who if He imprisons me imprisons me for ever, who if He puts me to death puts me to death for ever, and whom I cannot persuade with words or bribe with money - nay more, when there are two ways before me, one leading to Paradise and the other to Gehinnom, and l do not know by which I shall be taken, shall I not weep?'" It is possible that the reference to appearing before an earthly king may be connected with his appearance before Vespasian. At the moment of his death, he said to his disciples: "Remove the vessels so that they shall not become unclean, and prepare a throne for Hezekiah the king of Judah who is coming to accompany me into the next world" (Ber. 28b).