Jacob Harold Gallinger (born March 28, 1837) was a Republican senator from New Hampshire who served in the United States Senate from December 7, 1885, to March 3, 1919. A historical member of Congress, he represented the state of New Hampshire in the Senate for seven terms, reflecting a long and sustained tenure in national office. He is identified in congressional records under the bioguide ID G000023.

During his time in the Senate, Gallinger served as a member of the Republican Party and held office continuously until his service ended in 1919. His career in the Senate spanned more than three decades, marking him as a significant New Hampshire political figure of his era. Gallinger is remembered primarily for his extended service as a United States senator from New Hampshire between 1885 and 1919.