Son of Joseph Onderdonck, a farmer, and Dorothy Monfoort. Henry commonly rendered his name with a "Jr."; it is supposed that he did so to distinguish his name from that of his eminent relative, Henry Ustick Onderdonk (1789-1858), the Protestant Episcopal Bishop of Pennsylvania. Henry Onderdonk, Jr., graduated from Columbia College in 1827; received degree of A. B. from Harvard in 1828; Professor at Union Hall Academy at Jamaica, L. I.; author of "Revolutionary Incidents in Queens County," "History of Queens County," "Rise and Growth of Friends in Long Island and New York," "Suffolk and Kings Counties in the Olden Times," "Bibliography of Long Island." He also wrote the account of battle of Long Island for Bancroft's History of the United States.

He married Maria Hegeman Onderdonk (1801-1875), daughter of George Onderdonk and Sarah Rapalije in 1828, and had two children, Elizabeth (b. September 19, 1829) and Adrian ( b. December 27, 1831, Long Island; d. March 05, 1888, Flower Hill, L.I.).

Son of Joseph Onderdonck, a farmer, and Dorothy Monfoort. Henry commonly rendered his name with a "Jr."; it is supposed that he did so to distinguish his name from that of his eminent relative, Henry Ustick Onderdonk (1789-1858), the Protestant Episcopal Bishop of Pennsylvania. Henry Onderdonk, Jr., graduated from Columbia College in 1827; received degree of A. B. from Harvard in 1828; Professor at Union Hall Academy at Jamaica, L. I.; author of "Revolutionary Incidents in Queens County," "History of Queens County," "Rise and Growth of Friends in Long Island and New York," "Suffolk and Kings Counties in the Olden Times," "Bibliography of Long Island." He also wrote the account of battle of Long Island for Bancroft's History of the United States.

He married Maria Hegeman Onderdonk (1801-1875), daughter of George Onderdonk and Sarah Rapalije in 1828, and had two children, Elizabeth (b. September 19, 1829) and Adrian ( b. December 27, 1831, Long Island; d. March 05, 1888, Flower Hill, L.I.).