Authors born in 1866
- Abraham Flexner Biographer, 1866
- Addison Webster Moore Philosopher, 1866
- Alfred Werner Scientist, 1866
- Allen Tucker Artist, 1866
- Anne Reeve Aldrich Poet, 1866
- Anne Sullivan Macy Teacher, 1866
- Arnold Ehret Educator, 1866
- Arthur Cleveland Bent Ornithologist, 1866
- Arthur Keith Anthropologist, 1866
- Beatrix Potter Writer, 1866
- Benedetto Croce Philosopher, 1866
- Bert Leston Taylor Columnist, 1866
- Butch Cassidy Criminal, 1866
- Carlos Montezuma Activist, 1866
- Charles Davenport Scientist, 1866
- Charles F. Haanel Writer, 1866
- Charles Lane Poor Astronomer, 1866
- Charles Nicolle Scientist, 1866
- Christian D. Larson Author, 1866
- Claude C. Hopkins Businessman, 1866
- David F. Houston Businessman, 1866
- Edmund Vance Cooke Philosopher, 1866
- Elisabeth Leseur Spirituality, 1866
- Elizabeth von Arnim Novelist, 1866
- Emilie Loring Novelist, 1866
- Ernest Dimnet Clergyman, 1866
- Ernest MacBride Biologist, 1866
- Ernest Starling Physiologist, 1866
- G. I. Gurdjieff Philosopher, 1866
- Gelett Burgess Poet, 1866
- Georg Groddeck Psychiatrist, 1866
- Georg Jensen Founder, 1866
- George Ade Writer, 1866
- George Barr McCutcheon Novelist, 1866
- George Gurdjieff Teacher, 1866
- George Pierce Baker Educator, 1866
- Georges Besancon Founder, 1866
- H. G. Wells Novelist, 1866
- James J. Corbett Boxer, 1866
- Lincoln Steffens Reporter, 1866