Thomas Low Nichols (December 13, 1815 – July 8, 1901) was an American physician, journalist, writer, and advocate for a number of causes including free love, hydrotherapy, food and health reform, vegetarianism and spiritualism.

Born in Orford, New Hampshire, Nichols initially studied medicine at Dartmouth College but dropped out and became a radical journalist, working for newspapers in Lowell and New York.

His tenure as an editor and proprietor of the Buffalonian led to a brief prison sentence for libel, documented in his work Journal in Jail (1840).

Nichols and his wife were associated with Josiah Warren's Modern Times community before founding the Memnonia Institute in Yellow Springs, Ohio, which eventually failed.

After converting to Roman Catholicism, the couple moved to London to escape the American Civil War, where Nichols continued writing, founded the Co-operative Sanitary Company, and advocated for various causes including temperance, dress reform, and vegetarianism.

[5] Later, the couple founded a school for training water-cure therapists and published several books on health, food and other reforms.

[4] In Nichols' Monthly, he partially published an epistolary utopian story, which he infused with his beliefs about free love, universal suffrage and libertarianism.

[7] In 1856, the couple left and founded a "school of life", called the Memnonia Institute, based in Yellow Springs, Ohio.

[2] Nichols published two further novels Uncle Angus (1864) and Jerry (1872), as well as a best-selling autobiography Forty Years of American Life in 1864.

The couple campaigned for temperance and dress reform and against military conscription, vivisection, vaccinations and capital punishment.