American publisher who was also a Lutheran minister, religious journalist, Prohibition Party publicist, and spelling reformer.

Funk graduated from Wittenberg College, Springfield, Ohio, in 1860 and was ordained a Lutheran minister the following year. Resigning his pulpit in 1872 he traveled in Europe and the Middle East. After his return to the United States he helped edit the Christian Radical. Funk entered the publishing business in 1876, his first publication being an aid to ministers, the Metropolitan Pulpit.

In 1877, with a former classmate, Adam Willis Wagnalls, he founded I.K. Funk & Company, afterward (from 1891) Funk & Wagnalls (Funk & Wagnalls dictionaries) Company, in New York City. The firm became best known for A Standard Dictionary of the English Language (1st ed., 1893; subsequent editions entitled A New Standard Dictionary of the English Language).