Tadao (written: 忠雄, 忠夫, 忠男, 忠生, 忠郎 or 理男) is a masculine Japanese given name. Notable people with the name include:
Tadao Ando (安藤 忠雄) (born 1941), Japanese architectAoyama Tadao (青山 忠雄) (1651–1685), Japanese daimyōTadao Baba (born 1944), Japanese motorcycle engineerTadao Chino (千野 忠男) (1934–2008), Japanese bankerTadao Higuchi (樋口 忠男) (1916–1992), Japanese photographerTadao Horie (堀江 忠男) (1913–2003), Japanese footballer and managerTadao Ikeda (池田 忠雄) (1905–1964), Japanese screenwriter and film directorTadao Kasami (嵩 忠雄) (1930–2007), Japanese information theoristTadao Kikumoto, Japanese inventor and engineerTadao Kobayashi (小林 忠生) (born 1930), Japanese footballer and managerTadao Mitome (三留 理男) (born 1938), Japanese photographerTadao Nagahama (長浜 忠夫) (1936–1980), Japanese anime directorTadao Nakamura (born 1947), Japanese golferTadao Oda (小田 忠雄) (born 1940), Japanese mathematicianTadao Onishi (大西 忠生) (1943–2006), Japanese footballerTadao Sato (佐藤 忠男) (born 1930), Japanese film critic and theoristTadao Sawai (沢井 忠夫) (1938–1997), Japanese musicianTadao Takayama (高山 忠雄) (1904–1980), Japanese footballerTadao Tannaka (淡中 忠郎) (1908–1986), Japanese mathematicianTadao Tominari (冨成 忠夫) (1919–1992), Japanese photographerTadao Tomomatsu, American actorTadao Tosa (土佐 忠雄) (born 1942), Japanese diverTadao Uesako (上迫 忠夫) (1921–1986), Japanese gymnastTadao Umesao (梅棹 忠夫) (1920–2010), Japanese anthropologistTadao Watanabe (渡辺 忠雄), Japanese politicianTadao Yanaihara (矢内原 忠雄) (1893–1961), Japanese economist and academicTadao Yasuda (安田 忠夫) (born 1963), Japanese sumo and professional wrestler