| Honorific-Prefix: | His Excellency |
| Antoine Stillemans | |
| Bishop of Ghent | |
| Diocese: | Ghent |
| See: | St Bavo's |
| Predecessor: | Henri-Charles Lambrecht |
| Successor: | Emilius Seghers |
| Other Post: | Superior of the St. Joseph Minor Seminary |
| Ordination: | 20 September 1856 |
| Consecration: | 27 January 1890 |
| Birth Date: | 10 December 1832 |
| Birth Place: | Sint-Niklaas, East Flanders, Belgium |
| Buried: | Ghent |
| Motto: | Vivat Jesus! |
| Coat Of Arms: | Coat of arms of Antonius Stillemans.png |
Antoon Stillemans (10 December 1832, Sint-Niklaas – 5 November 1916, Ghent) was for 26 years the twenty-fourth bishop of Ghent, in Belgium.
Stillemans began studies at the St. Joseph Minor Seminary of Sint-Niklaas in 1846. In 1853 he enrolled at the major seminary in Ghent, earning a doctoral degree in philosophy at the University of Leuven in 1860. Stillemans' brother,, also became a priest.
He was named in 1867 Superior of the St. Joseph Minor Seminary of Sint-Niklaas, for 21 years. He became president of the Major seminary in 1888 and canon of the cathedral chapter of Ghent and member of the episcopal council. He was canon elect after the sudden death of Henri-Charles Lambrecht. He promoted the Gothic Revival, and had the current Episcopal Palace in Ghent restyled as well building a new major seminary in Ghent.
He named his brother Pierre-Louis Stillemans an honorary canon of St-Bavo.
In 1899, under pressure from the royal court and Minister Woeste, he suspended Adolf Daens, a radical priest in Aalst. He promoted the social cultural movement of Flanders. In 1902 he consecrated the new church attached to Dendermonde Abbey. In 1906, he celebrated his golden jubilee as priest and, in 1914, his silver jubilee as bishop of Ghent. He was honored with the sacred pallium with papal permission at the end of his career. A street was named in his honor in Sint-Niklaas, as well as a stained-glass window inside the town hall, he gifted Sint-Niklaas with a large copy of his portrait. The colors of the city, blue and yellow are reflected in his heraldic episcopal crest.
After his death he left his crosier to the main church of Sint-Niklaas where he was baptized. He was succeeded by Mgr. Emilius Seghers.