Isaac Newton Seligman (July 10, 1855 – September 30, 1917) was an American banker and communal worker.

At Columbia, he was one of the crew that won the university eight-oar college race on Saratoga Lake in 1874 over Yale, Harvard, and nine other schools.

He was a trustee of nineteen important commercial, financial, and other institutions and societies, including the Munich Life Assurance Company, St. John's Guild, and the McKinley Memorial Association.

He was a member of the Committee of Seventy, of Fifteen, and of Nine, each of which attempted at various times to reform municipal government in New York; of the last-named body he was chairman.

His portrait, three-quarter length seated, was painted by the Swiss-born American artist Adolfo Müller-Ury (1862–1947) but is now missing.