Union Defenders of Kansas, 1865 (scroll down the page for Johnson County)
Kansas Adjutant General's Report 1861-1865. Searchable index here. Includes the names of all troops who served in the Kansas volunteer regiments during the Civil War.
KS State Guard, 1917 - 1919, 7th Battalion, Olathe
KS State Guard, 1917 - 1919, Overland Park Battalion
Kansas State Historical Society
WWII Kansas Veterans Index (searchable index)
The Virtual Wall - Vietnam Veterans Memorial: Kansas
Sons of Union Veterans of the Civil War Graves Database
US Dept. of Veterans Affairs: National Cemeteries: Gravesite Locator
Digital Cemetery; Photo-index of Johnson County cemeteries. Each cemetery has a listing of identified veterans as well as desigation in the listing.