Clay Township is one of fourteen townships in Cass County, Indiana, United States, and one of the seventeen townships sharing the name in the state. As of the 2020 census, its population was 2,842 (up from 2,817 at 2010) and it contained 1,177 housing units.
Clay Township was organized in 1832. It was named for Henry Clay, three-term Speaker of the House of Representatives and Secretary of State.
Thompson Barnett House was listed on the National Register of Historic Places in 1986.
According to the 2010 census, the township has a total area of , of which (or 99.10%) is land and (or 0.90%) is water.
The township contains two cemeteries: Bethel and Wilson.