Plain Township is one of seventeen townships in Kosciusko County, Indiana, United States. As of the 2020 census, its population was 8,819 (up from 7,698 at 2010) and it contained 4,129 housing units.
The Robert Orr Polygonal Barn was listed on the National Register of Historic Places in 1992.
According to the 2010 census, the township has a total area of , of which (or 94.51%) is land and (or 5.49%) is water.
(This list is based on USGS data and may include former settlements.)