Tadeusz Mikołaj Thullie (born 6 December 1741 in Warsaw, died 14 April 1843 in Lwów)[1] was the last Royal Secretary of King Stanisław August Poniatowski.

[3] He was the son of Adam Thullie, lieutenant general of the Polish army, and Katarzyna née Fontana, a sister of royal architect Jakub Fontana.

[4] Tadeusz's grandfather, Jan Thullie, had been brought to Poland from France by hetman Adam Mikołaj Sieniawski.

After arriving in Poland, he became chief medical officer of the Polish army and a lay judge in Lwów.

[6] From his first marriage with Joanna Głębocka, Tadeusz Thullie had two sons and two daughters.