Shannon County is a county in the southern portion of the U.S. state of Missouri. As of the 2020 census, the population was 7,031. Its county seat is Eminence. The county was officially organized on January 29, 1841, and was named in honor of George F. "Peg-Leg" Shannon, a member of the Lewis and Clark Expedition. It is the second-largest county by area in Missouri.

On March 18, 1925, one of the deadliest tornado outbreaks in recorded history generated at least twelve significant tornadoes and spanned a large portion of the midwestern and southern United States. In all, at least 751 people were killed and more than 2,298 were injured, making the outbreak the deadliest tornado outbreak, March 18 the deadliest tornado day, and 1925 the deadliest tornado year in U.S. history. The outbreak generated several destructive tornadoes in Missouri, Illinois, and Indiana on the same day, as well as significant tornadoes in Alabama and Kansas. In addition to confirmed tornadoes, there were undoubtedly others with lesser impacts, the occurrences of which have been lost to history.