Lillis is an unincorporated community in Marshall County, Kansas, United States.
Lillis was named for Rev. T. F. Lillis. A post office was opened in Lillis in 1910, and remained in operation until it was discontinued in 1958.
The Lillis Gymnasium is on the National Register of Historic Places.
The community and nearby rural areas are served by Vermillion USD 380 public school district.