Simonis is both a surname and a given name. Notable people with the name include:
Adrianus Johannes Simonis (1931–2020), Dutch Roman Catholic cardinal and former archbishop of Utrecht Eugène Simonis or Eugen Simonis (1810–1893), Belgian sculptor and architect Heide Simonis (1943–2023), German politician Kazys Šimonis (1887–1978), Lithuanian artist Simonis Palaiologina (1294– after 1336), Byzantine princess and third wife of Stefan Uroš II Milutin of Serbia Simonis Starovolsci (1588–1656), Polish scholar
See also Simono, a Native American group that lived in Nuevo León and later in eastern Texas.