Clusius may refer to:
Carolus Clusius (1526–1609), Flemish doctor and botanist Klaus Clusius (1903–1963), German physical chemist Ulmus 'Clusius', a hybrid elm cultivar
See also Gentiana clusii, commonly known as flower of the sweet-lady or Clusius' gentian Clusia, the type genus of the flowering plant family Clusiaceae