DeWitt Clinton Littlejohn (February 7, 1818 – October 27, 1892) was a brevet brigadier general in the Union Army and a United States representative from New York during the Civil War.

He did not complete college, and instead engaged in several profitable mercantile pursuits, acting for a time as a forwarder of fresh produce on the lakes and canals of the region.

In 1861, Littlejohn was influential in the backroom politics to select Ira Harris over Horace Greeley as the Republican Party's nominee to run for the U.S. Senate to succeed William H. Seward, who had not run for re-election, expecting to join President Abraham Lincoln's cabinet.

He trained his troops at Camp Patterson near Baltimore, where it was stationed until November, when it was ordered to be relocated to federal-occupied New Orleans.

[1] In 1870, the Republican state convention nominated Littlejohn for Lieutenant Governor of New York on the ticket with Stewart L. Woodford, but he declined to run.