Isaac Knapp (January 11, 1804 – September 14, 1843)[2] was an American abolitionist printer, publisher, and bookseller in Boston, Massachusetts.

[4][5][page needed] With his friend William Lloyd Garrison he printed the anti-slavery Liberator newspaper, from 1831 to 1839.

He frequently used blank pages at the end of the books he published to advertise a large and ever-changing list of abolitionist publications available from him.

In the July 24, 1840, issue, there is an advertisement for the abolitionist printers Dow and Jackson "successors to Isaac Knapp".

It was thus he became depressed in spirit, and, instead of calmly submitting to the stroke of adversity, vainly sought to find relief from his sorrows (as millions have done before) in the intoxicating bowl."