St Denys' Church, Sleaford is a medieval church located in Sleaford, Lincolnshire, England. The oldest parts of the present building are the tower and spire. The spire stands 144 feet (44 metres) tall. A window tracery is dated to about the late 13th century. The Gothic nave, aisles and north transept were built in the 14th century. The church is a Grade I listed building, a term given to "buildings of exceptional interest".