Joseph Spencer (1790 – May 2, 1823) was an American lawyer and politician from New York.
He was born in Hartford, Connecticut, the son of Isaac Spencer who was Connecticut State Treasurer from 1818 to 1835.
Joseph Spencer graduated from Yale College in 1811, then studied law, was admitted to the bar, and practiced in Rochester, New York. On September 24, 1814, he married Elizabeth Selden (b. 1797), a sister of Samuel L. Selden and Henry R. Selden. Their only child was Elizabeth Selden Spencer (b. 1819).
Spencer was a member of the New York State Senate (8th D.) in 1823, and died a few days after the end of the regular session of the Legislature in Albany, New York. His widow married Amos B. Eaton in 1831, and became the grandmother of Elizabeth Selden Rogers.