Alexander Gilmore Cattell (February 12, 1816 – April 8, 1894) was a United States senator from New Jersey.

He was a member of the State constitutional convention in 1844 and moved to Philadelphia in 1846, where he engaged in business and banking.

In 1863, Cattell moved to Merchantville, New Jersey in 1863 and was elected as a Republican to the U.S. Senate to succeed John P. Stockton, whose seat was declared vacant, and served from September 19, 1866, to March 3, 1871.

Cattell was appointed by President Ulysses Grant to be a member of the first United States Civil Service Commission and served two years, resigning to accept the position of United States financial agent in London, serving in 1873 and 1874.

Cattell died in Jamestown, New York in 1894 and was interred in Colestown Cemetery in Cherry Hill, New Jersey.