Lewis Tappan (May 23, 1788 – June 21, 1873) was an American abolitionist who helped to secure freedom for the enslaved Africans aboard the Amistad.

Contacted by Connecticut abolitionists shortly after the Amistad arrived in port, Tappan devoted significant attention to the captive Africans.

He ensured the acquisition of high-quality lawyers for the captives, ultimately leading to their release after the case reached the United States Supreme Court.

Alongside his brother Arthur, Tappan not only secured legal assistance and acquittal for the Africans but also successfully bolstered public support and fundraising efforts.

Lewis Tappan initially supported the American Colonization Society (ACS), which promoted sending freed blacks from the United States to Africa, based on the assumption that this was their homeland, regardless of where they were born.

Frustrated by the slow progress of the ACS, Tappan and a sizable nucleus of men, including his brother Arthur, Theodore Dwight Weld, Gerrit Smith, Amos A. Phelps, and James Gillespie Birney, left the ACS to join what was to become known as the "immediatist" camp, who wanted to end slavery in the United States (US).

In December 1833, at Philadelphia, Lewis Tappan joined activists such as William Lloyd Garrison to form the American Anti-Slavery Society.

Lewis Tappan advocated intermarriage (at the time called "amalgamation") as the long-range solution to racial issues, as all people would eventually be mixed race.

Tappan characterized the arrival of the Amistad and its Africans on American shores as a "providential occurrence" that might allow "the heart of the nation" to be "touched by the power of sympathy.

"[citation needed] The Tappan brothers created chapters of the American Anti-Slavery Society (AAS) throughout New York state and in other sympathetic areas.

Lewis began a nationwide mailing of abolitionist material, which resulted in violent outrage in the South and denunciation by Democratic politicians, who accused him of trying to divide the Union.

Tappan attended each day of the trials and wrote daily accounts of the proceedings for The Emancipator, a New England abolitionist paper.

After achieving legal victory in the US Supreme Court, Tappan planned to use the Amistad Africans as the foundation for his dream to Christianize Africa.

[8] In 1846, Tappan was among the founders of the American Missionary Association (AMA), led by Congregational and Presbyterian ministers, both white and black.

During and after the American Civil War, Tappan and his brother Arthur worked from New York with the AMA on behalf of freedmen in the South.

Unwilling to reduce his commitment to U.S. government action against slavery in the southern states, Tappan and other radical political abolitionists denounced the Democratic Party as essentially pro-slavery.