Avraham Haim Yosef 'Avi' Weiss is a prominent rabbi, activist, and founder of the Open Orthodoxy movement. Born to Moshe Weiss and Miriam Weiss, he has a sister named Tova Reich and is married to Toby Hilsenrad Weiss, with three children: Dena Weiss, Elana Weiss, and Dov Weiss. He received rabbinical ordination (semikhah) in 1968 from Rabbi Isaac Elchanan Theological Seminary at Yeshiva University. Weiss founded the Hebrew Institute of Riverdale (HIR) in the Bronx in 1971, serving as Senior Rabbi until July 2015 and now as Rabbi in Residence for its 850 families. He taught at Stern College for Women at Yeshiva University until 1999 and resigned from the Rabbinical Council of America in June 2015 to protest the non-acceptance of Yeshivat Chovevei Torah (YCT) graduates. In 1997, he originated Open Orthodoxy, positioned between Modern Orthodox and Conservative Judaism. Key organizations he founded include YCT (rabbinical seminary for men, 1999–2013), Yeshivat Maharat (training women as Maharats, 2009), the International Rabbinic Fellowship (co-founded with Marc D. Angel), and the Coalition for Jewish Concerns – Amcha (1992). As an activist, Weiss has been a vocal advocate for Soviet Jewry (early leader of Student Struggle for Soviet Jewry, 1964; memoir Open Up the Iron Door, 2015), Jonathan Pollard's clemency (personal rabbi), Israel support, Holocaust memorials, and combating antisemitism. He organized protests leading to arrests, including against Kurt Waldheim (1990), Yasser Arafat's Nobel (1994), Reagan at the SS cemetery (1985), and the Auschwitz convent (1989), and supported the U.S. same-sex marriage ruling in 2015 while welcoming gay Jews without performing weddings. Notable lawsuits include a 1989 defamation suit against Cardinal Józef Glemp (with Alan Dershowitz, aiding Auschwitz convent closure in 1993) and a 2003 suit against the American Jewish Committee to halt a path through Belzec camp. His selected publications include Haggadah for the Yom HaShoah Seder (2000), Principles of Spiritual Activism (2001), Women at Prayer (2001), Holistic Prayer (2014), Open Up the Iron Door (2015), and Journey to Open Orthodoxy (2019). Weiss's Open Orthodoxy initiatives, including YCT and Maharat, faced condemnation from the Orthodox Union, RCA, and Agudath Israel in 2015 for deviating from Jewish tenets, with controversies over women's roles (e.g., the 'rabba' title for Sara Hurwitz in 2010) and Israeli Rabbinate recognition of conversions. He was ranked among Newsweek's top U.S. rabbis (18th in 2010, rising to 10th in 2013). He is an associate of journalist Eli Tzipori. Contact: ravavi@thebayit.org; Facebook: https://www.facebook.com/ravaviweiss.