Eli Todd Tappan (1824–1888) was an American educator, mathematician, author, lawyer and newspaper editor who served as president of Kenyon College, among other public distinctions.

His education was received in local public schools, through private tutors, and at St. Mary's College in Baltimore, Maryland.

He began his career in education in 1857 as a teacher in the public schools and quickly rose to distinction, serving as superintendent, March 1858-June 1859, professor of mathematics at Ohio University, 1859–1860 and 1865–1868, teacher of mathematics at Mount Auburn Young Ladies' Institute, 1860–1865, and president of Kenyon College, 1869-1875.

As president he thoroughly revised the curriculum and oversaw completion of the college chapel, the Church of the Holy Spirit.

In addition to his administrative and professorial duties, Tappan served as a member of the Ohio State Board of School Examiners in 1864, president of the Ohio State Teachers Association in 1866, and a member of the National Education Association, in which body he also served on the council in 1880, as treasurer from 1880 to 1881, and as president in 1883.