Universalist, Unitarian, & Unitarian Universalist Milestones
- Ezra Ripley (1 May 1751 Woodstock, Connecticut – 21 September 1841 Concord, Massachusetts) Minister, Temperance Movement Leader, Author
- Pete Seeger (3 May 1919 Manhattan, NY – 27 January 2014 Manhattan, NY) Singer, Songwriter, Political Activist
- May Sarton (3 May 1912 Wondelgem, Belgium – 16 July 1995 York, Maine) Poet, Novelist, Actor
- Horace Mann (4 May 1796 Franklin, Massachusetts – 2 August 1859 Yellow Springs, Ohio) Lawyer, Educator, U.S. Representative, Reformer
- Florence Nightingale (12 May 1820 Florence, Italy — 13 August 1910 London, England) Nurse, Author, Educator
- Edna Pearl Bruner (14 May 1906 Ruthven, Ontario, Canada – 3 August 1997) Universalist Church of America Field Worker, Minister, Religious Education Conference Leader
- Thomas Bradford Curtis (14 May 1911 St. Louis, Missouri – 10 January 1993 Allegan, Michigan) Lawyer, U.S Representative, USN Lieutenant Commander
- Margaret Fuller (23 May 1810 Cambridgeport, Massachusetts – 19 July 1850 Off Fire Island, New York) Author, Feminist, Women’s Rights Activist, Poet, Teacher, Journalist
- Ralph Waldo Emerson (25 May 1803 Boston, Massachusetts – 27 April 1882 Concord, Massachusetts) Minister, Essayist, Philosopher, Poet
- Julia Ward Howe (27 May 1819 New York City, New York – 17 October 1910 Portsmouth, Rhode Island) Women’s Rights Activist, Poet, Abolitionist
- Horace Heffren (27 May 1831 Dryden, New York – 20 May 1883 Salem, Indiana) USA Colonel, Mason, State Senator, State Representative
- David Pickering (28 May 1788 Richmond, New Hampshire – 6 January 1859 Ypsilanti, Michigan) Minister, Journalist
- John Eliot (31 May 1754 Boston, Massachusetts – 14 February 1813 Boston, Massachusetts) Minister, Historian
In U/U/UU History
- 26 May 1825 – The American Unitarian Association was formed in Boston.
- 24 May 1944 – The Unitarian Church Of The Larger Fellowship formed.
- 23 May 1960 – At meetings in John Hancock Hall in Boston, Unitarians and Universalists voted to consolidate.
- 15 May 1961 – Universalist Church Of America and American Unitarian Association merged to formed the Unitarian Universalist Association.