Isaac Reingold (Yitskhok, Itsik, יצחק רײנגאָלד) is the pen name of Isaac Toomim ( תּאומים יצחק) 1873-1903), a Russian-born American poet, lyricist, and singer.

Born in 1873 in Oder, near Loytsk (Lutsk), Volhynia, Ukraine, into a Chasidic family. He received a strict religious education; his father was bitterly opposed to the Enlightenment and a fervent believer in brotherhood and equality.

His poetry and his couplets—often set to melodies of famous English-language popular songs—were popular with working-class audiences. He sang well and performed in concert halls and workers' gatherings. His songs were published in: Lider-magazin, Di idishe bihne, and Teglikher idisher kuryer. He also wrote an opera, Al nahares bovl (By the rivers of Babylon).

He died October 21, 1903, in Chicago.