John Allen Wilcox (April 18, 1819 – February 7, 1864) was a politician from Mississippi and Texas who served in the United States House of Representatives in the early 1850s and then in the Confederate Congress during the American Civil War.
Wilcox was born in Greene County, North Carolina, a son of Ruben and Sarah (Garland) Wilcox. One brother, Cadmus Wilcox, would later become a general in the Confederate States Army. It is likely that Wilcox was raised and educated in Tipton County, Tennessee, where the family moved. Moving to Mississippi and entering politics, he served as secretary of the State Senate. He enlisted in the United States Army during the Mexican-American War, serving as lieutenant colonel of the 2nd Mississippi Volunteer Infantry. When hostilities ceased, he returned to Mississippi and practiced law in Aberdeen.
In 1850, he was elected to Congress as a Whig, defeating future Civil War general Winfield S. Featherston. Two years later, Wilcox was defeated for re-election. In 1853, he moved to San Antonio, Texas, and resumed his law practice. He briefly dabbled in the Know Nothing political movement, serving as a presidential elector in 1856, but then joined the Democratic Party in 1858, attending the National Convention that year.