Gedalyah ben Achikam גדליהו בן אחיקם

Son of Achikam ben Shafan—of a house that stood by the prophets for generations: his grandfather Shafan was the scribe of King Yoshiyahu and read him the scroll of the Torah found in the Temple, and his father Achikam saved Yirmiyahu from death when men demanded his life.

After the Temple was destroyed Nevuzaradan left the poorest in the land and set Gedalyah over them; he took his seat at Mitzpah. Those scattered in the neighbouring lands began to return to him, and they "gathered wine and summer fruits in great abundance". Yirmiyahu stayed with him. For the first time in years there was hope of living on their own land, even under a foreign power.

Yochanan ben Kareach warned him that Yishmael ben Netanyah had been sent by Baalis, king of Ammon, and asked leave to forestall the murder. Gedalyah answered: "You speak falsely of Yishmael"—and would not accept the report. In the seventh month Yishmael came with ten men; they ate bread together at Mitzpah, and there Gedalyah was killed, along with the Judeans who were with him and the Babylonian garrison.

The Gemara draws a hard lesson from him: he did not accept the slander—and rightly—but he should have taken care, and Scripture ascribes to him the death of those who fell with him. The Tanakh names no day, only the month; the fast is kept on 3 Tishrei, while by a tradition cited in Rosh Hashanah 18b he was killed on Rosh Hashanah and the fast was moved to the third. So the death of one man entered the four fasts of the destruction beside the fall of the Temple.