Cass Township is one of fifteen townships in Greene County, Indiana, USA. As of the 2020 census, its population was 299, down from 358 at 2010.
According to the 2010 census, the township has a total area of , of which (or 97.46%) is land and (or 2.49%) is water. The streams of Doans Creek, Gilbert Creek, Mud Creek and Woodhouse Branch run through this township.
The township contains three cemeteries: Gilbreath, Old Slinkard and Slinkard.