Sadao (written: , , or in katakana) is a masculine Japanese given name. Notable people with the name include:
*, Japanese actor and musician
*, Imperial Japanese Army general, politician, and political philosopher
*, Japanese classical composer
*, Japanese politician
*, Japanese gay erotic artist
*, Japanese sport wrestler
*, Japanese sumo wrestler
*, United States Army soldier and Medal of Honor recipient
*, Japanese film director and screenwriter
*, Japanese sport wrestler
*, Japanese astronomer
*, Japanese entomologist
*, Japanese sumo wrestler
*, Japanese printmaker
*, Japanese jazz musician
*, Japanese politician
*, Japanese film director and screenwriter
{{given name
Japanese masculine given names
Masculine given names