Philip Reis Alstat (July 15, 1891 – November 29, 1976) was a well-known American Conservative rabbi, teacher, chaplain, speaker and writer. Born in Kaunas (formerly, Kovno), Lithuania, he came to the United States in 1898, studying at City College of New York (A.B., 1912), Columbia University (A.M., 1915), and the Jewish Theological Seminary of America (JTS), where he received semikhah, rabbinic ordination, in 1920, and the Doctor of Divinity degree (honoris causa), in 1966.

For many years, he lived at JTS, serving as an informal and unofficial in-house counselor and mentor for generations of rabbinical students. In addition to his experience as a pulpit rabbi in New York synagogues including Congregation Shaare Zedek (New York City) on Manhattan's upper-West side, he was a chaplain for a number of New York institutions, including The Tombs, the Manhattan Detention Complex, and oversaw courses for prospective converts to Judaism in New York City. For more than four decades, he wrote the widely syndicated weekly newspaper column, Strange to Relate.

Alstat, the brother of Rabbi Murray Alstet, was "one of the early pioneers" of the Conservative movement, attending rabbinical school with classmates who would become many of the teachers and leaders of the movement. He graduated in 1920, in the same class as Max Kadushin, and one year before future JTS Chancellor, Louis Finkelstein. Early in his rabbinic career, he served in a number of synagogue pulpits, including Temple Sons of Israel, in White Plains, New York, 1920–21; Temple Beth Elohim, 1921–25; Temple Adath Israel, The Bronx, NY, 1925–30; and Temple Bnai Israel-Sheerith Judah, in upper Manhattan, 1933–1955., before leaving to focus on other endeavors, including teaching, writing, and chaplaincy service in New York prisons, hospitals, and senior citizen facilities.

Alstat was an ardent Zionist and an early representative of the World Zionist Organization (WZO). In 1935, he spoke to a combined meeting of the Zionist Organization of America (ZOA) and Hadassah, declaring that "the solution of the problem of world Jewry lies in the rebuilding of the national Jewish homeland in Palestine." He stated that

World Jewry is now wrestling with a complexity of major problems, such as the combating of anti-Semitism which is rearing its ugly head in various lands; finding a refuge for the persecuted and exiled Jews of Germany; widening the ever-narrowing channels of economic opportunities for Jews; and preserving and transmitting the spiritual heritage of the Jewish people. All of these problems can be solved in large measure by accelerating the tempo of the rebuilding of the Jewish national homeland in Palestine.

In addition to his positions with the WZO and ZOA, he was on the Executive Boards of many other organizations, including the United Synagogue of America, the Jewish National Fund, and the United Palestine Appeal, and an active member of others, including the Rabbinical Assembly, and the New York Board of Rabbis.

He worked as a prison chaplain at the Manhattan Correctional Facility ("The Tombs") for three decades, and served as secretary of the National Council of Jewish Prison Chaplains, sharing information with rabbis who worked with inmates and prison staff in other facilities throughout the United States. He explained his vision of prison chaplaincy by saying that, "My goals are the same as those of the prison authorities—to make better human beings. The only difference is that their means are discipline, security, and iron bars. Mine are the spiritual ministrations that operate with the mind and the heart." He would sometimes take rabbinical students with him on his visits, schooling them on counseling techniques he had developed over the years. When he retired from prison chaplaincy work in 1974, as the city was preparing to tear down part of the facility (although it was eventually replaced by new buildings), he reflected over his career, noting that prison conditions had markedly improved, especially since the 1970 "upheavals" at The Tombs. He said there was "much more cordiality and serenity – if it's possible to have any serenity in a prison." In addition to his work as a prison chaplain, Alstat also served as a chaplain for Jewish Memorial Hospital, Sydenham Hospital, and the Williams Memorial Residence, operated by the Salvation Army.

His syndicated column, "Strange to Relate," was printed in many Jewish papers, and led to many invitations to speak at Jewish community events. He was described as a "prominent American lecturer on Jewish oddities, curiosities, and fantasies." However, while his column and some of his presentations focused on oddities—issues that were "strange to relate" – Alstat was also well known for speaking his mind on the most serious of issues, delivering important messages in eloquent ways. In an American Jewish History article on the Rabbinical Assembly (RA), the author noted that during Alstat's early time in the rabbinate, the RA's concerns were about America and the Conservative movement, but it was rare to deal with the problems "plaguing the American rabbi." Rabbi Alstat's address to the 1929 annual RA convention was especially noteworthy because he shared such concerns in a public forum, when he delivered the presentation, Observations on the Status of the Rabbinate. That address included he following words: