(Tadeusz Mazowiecki) Rueda de prensa de Felipe González con el primer ministro de Polonia. Poo

''Tadeusz'' is a Polish language, Polish first name, derived from Thaddeus, Thaddaeus.

Tadeusz may refer to:

* Tadeusz Bór-Komorowski (1895–1966), Polish military leader
* Tadeusz Borowski (1922–1951), Polish writer and The Holocaust survivor
* Tadeusz Boy-Żeleński (1874–1941), Polish gynaecologist, writer, poet, art critic, translator of French literary classics and journalist
* Tadeusz Brzeziński (1896–1991), Polish consular official and the father of President Jimmy Carter's national security adviser, Zbigniew Brzezinski
* Tadeusz Czeżowski (1889–1981), Polish philosopher and logician
* Tadeusz Dołęga-Mostowicz (1898–1939), Polish journalist and author of over a dozen popular novels
* Tadeusz Drzazga (born 1975), Polish weightlifter
* Tadeusz Hollender (1910–1943), Polish poet, translator and humorist
* Tadeusz Jordan-Rozwadowski (1866 – 1928) was a Polish military commander, diplomat, and politician, a founder of the modern Polish Republic
* Tadeusz Kantor (1915–1990), Polish artist and theatre-maker
* Tadeusz Kassern (1904–1957), Polish composer
* Tadeusz Wladyslaw Konopka, birth name of Ted Knight (1923–1986), American actor
* Tadeusz Konwicki (1926–2015), Polish writer
* Tadeusz Kościuszko (1746–1817), Polish–Lithuanian military leader and national hero, and American Revolutionary War general
* Tadeusz Kotarbiński (1886–1981), pupil of Kazimierz Twardowski
* Tadeusz Krwawicz (1910–1988), Polish pioneer in medicine
* Tadeusz Kurcyusz (1881–1944), commandant of Narodowe Sily Zbrojne
* Tadeusz Łomnicki (1927–1992), Polish actor
* Tadeusz Michalik (born 1991), Polish Olympic bronze medalist in Greco-Roman wrestling at the 2020 Olympics
* Tadeusz Miciński (1873–1918), Polish poet and playwright
* Tadeusz Pietrzykowski (1917–1991), Polish boxer and Polish Armed Forces soldier, known as the "boxing champion of Auschwitz"
* Tadeusz Piotrowski (mountaineer) (1940–1986), mountaineer and writer
* Tadeusz Piotrowski (sociologist) (born 1940), sociologist and author of books about Holocaust and the history of Poland
* Tadeusz Rejtan (1742–1780), Polish nobleman
* Tadeusz Romer (1894–1978), Polish diplomat and politician
* Tadeusz Różewicz (1921–2014), Polish poet and writer
* Tadeusz Rut (1931–2002), Polish hammer thrower
* Tadeusz Sapierzyński (born 1958), Polish army officer
* Tadeusz Swietochowski (1934–2017), American historian and Caucasologist
* Tadeusz Ślusarski (1950–1998), Polish Olympic gold medalist in pole vault at the 1976 Olympics
* Tadeusz Tański (1892–1941), Polish automobile engineer and the designer of, among others, the first Polish serially-built automobile
* Tadeusz Tomaszewski (born 1959), Polish politician, Member of the Parliament
* Tadeusz Ważewski (1896–1972), Polish mathematician
* Tadeusz Żychiewicz (1922–1994), Polish journalist, art historian and publicist

In fiction, Tadeusz can refer to:
* Tadeusz Soplica, the titular character of ''Pan Tadeusz'', an 1834 epic poem by Adam Mickiewicz

{{given name
Polish masculine given names