David Allen Smalley (April 6, 1809 – March 10, 1877) was a United States federal judge.
Smalley was born in Middlebury, Vermont on April 6, 1809. He graduated from the academy in St. Albans, read law with his uncle, and was admitted to the bar. He practiced in Jericho, Vermont, where he was also postmaster from 1831 to 1836.
He subsequently relocated, first to Lowell, Vermont, and then to Burlington, Vermont. He was a member of the Vermont State Senate from 1843 to 1844. He practiced law in Burlington with different partners at different times. One partner was Edward J. Phelps, and the firm of Smalley & Phelps included George F. Edmunds among those who studied law in their offices.
At the 1852 Democratic National Convention he was Vice Chairman of the Vermont delegation, a member of the platform committee and was selected to serve as Vermont's member of the Democratic National Committee.
President Franklin Pierce appointed him Collector of Customs for the District of Vermont in 1853 and he served until 1857. Again a delegate at the 1856 Democratic National Convention held in Cincinnati, Ohio, he was reappointed to the National Committee, and he served Chairman from 1856 to 1860.
On February 2, 1857, Smalley was nominated by President Franklin Pierce to the seat on the United States District Court for the District of Vermont vacated by the death of Samuel Prentiss. Smalley was confirmed by the United States Senate on February 3, 1857, and received his commission the same day.