Rabbi Chanina, or Chananiah, Segan HaKohanim was a Tanna of the first generation who lived at the time of the destruction of the Second Temple. His title comes from his office: he was the segan, the deputy of the Kohen Gadol, who oversaw the service of the kohanim and stood ready to replace the High Priest. He explained it himself: "Why is a segan appointed? So that if the High Priest becomes unfit, he may enter and serve in his place" (Sotah 42a). His son was Rabbi Shimon ben HaSegan.

After the destruction he testified about what he had seen in the Temple. The Mishnah (Eduyot 2:1) records that he "testified concerning four matters", among them that the priests never refrained from burning meat defiled by a derivative impurity together with meat defiled by a primary source of impurity. This statement opens a long Talmudic discussion (Pesachim 14a) named after him. He also testified: "All my days I never saw a hide taken out to the place of burning" (Eduyot 2:2), and related: "My father would reject blemished animals from upon the altar" (Zevachim 9:3). The Mishnah further records that the household of Rabbi Chananiah Segan HaKohanim prostrated themselves at a fourteenth place in the Temple, facing the wood store, following a tradition from their fathers that the Ark had been hidden there (Shekalim 6:1).

In Pirkei Avot (3:2) he taught: "Pray for the welfare of the government, for were it not for the fear it inspires, every man would swallow his neighbor alive."

According to Megillat Ta'anit Batra, he was killed together with Rabban Shimon ben Gamliel and Rabbi Yishmael ben Elisha, among the Ten Martyrs, on 25 Sivan; for this reason the day was set as a fast of the righteous, as recorded in the Arba'ah Turim and the Shulchan Aruch (Orach Chayim 580). A folk tradition attributes to him a grave, shared with Rabbi Zechariah ben HaKatzav, near Kfar Chananiah in the Galilee.