Rene Gagnon, American soldier (d. 1979)
René Arthur Gagnon (March 7, 1925 – October 12, 1979) was a United States Marine Corps corporal who participated in the Battle of Iwo Jima during World War II.

Gagnon was generally known as being one of the Marines who raised the second U.S. flag on Mount Suribachi on February 23, 1945, as depicted in the iconic photograph Raising the Flag on Iwo Jima by photographer Joe Rosenthal. On October 16, 2019, the Marine Corps announced publicly (after an investigation) that Corporal Harold Keller, not Gagnon, was in Rosenthal's photo. Gagnon was one of three men who were originally identified incorrectly as flag-raisers in the photograph (the others being Hank Hansen and John Bradley).The first flag that had been raised was deemed too small. Later that day, Gagnon, a runner in the 5th Marine Division, was given a larger flag to take up the mountain. A photo of the second flag-raising became famous and was widely reproduced. After the battle, Gagnon and two other men who were identified as surviving second flag-raisers were reassigned to help raise funds for the Seventh War Loan drive.

The Marine Corps War Memorial in Arlington, Virginia, is modeled after Rosenthal's photograph of six Marines raising the second flag on Iwo Jima.