Antonis Fosteridis (Greek: Ἀντώνης Φωστερίδης, also Φωστηρίδης, 1912–1979), also known by the nom de guerre of Çauş Anton (Τσαούς Αντών), was a Pontus-born Greek nationalist, anticommunist partisan during the Axis occupation of Greece, who served in the Hellenic Army during the Greek Civil War and, during peace time, was elected member of the Hellenic Parliament.

Antonis Fosteridis (also Fostiridis) was born in 1912 in the village of Eroukli of the Bafra, Pontus region of the Ottoman Empire. His father Kyriakos fought with the Pontic irregulars against the Nationalist Turkish forces in the region in the period 1918–22, and emigrated to the Greek mainland with the enforcement of the population exchange between the two nations. The family, whose members were all mostly turkophone, stayed initially in the Oropedio village and then made its home at Krinides.

Fosteridis was enlisted in the Greek army and served as a sergeant of the artillery. Ηe participated in the failed 1935 military coup attempt by officers loyal to Eleftherios Venizelos and was dishonorably discharged from the army.

When war was declared in October 1940 between Greece and Italy, Fosteridis was recalled and he took part in the battles fought in the mountains of Southern Albania. For the bravery he showed in combat, Fosteridis reached the rank of Second Lieutenant, the highest rank for an NCO.

On 6 April 1941, Germany invaded Greece. The war ended on the 1st of June of the same year with Greece's capitulation, after Crete was captured. The country was occupied by the European Axis powers and their allies. Bulgaria occupied and annexed the regions of Eastern Macedonia and Thrace.

Bulgaria integrated the occupied region as "new countries", carrying the title Belomórie (in Bulgarian Беломорие) and commenced a policy of violent assimilation of the native population. The immediate result of the repressive measures was the exodus of a significant number of former local administrators of the Greek government, priests, teachers, physicians, business people, and others, who sought refuge mostly in German-occupied Macedonia. The occupying authorities forbid the use of the Greek language in all signs and official documents, and expropriated lands and houses owned by Greeks to settle there Bulgarian citizens.

In late September 1941, in reaction to these measures, small groups of partisans and irregulars, organized mostly by the Communist Party, attacked Bulgarian military, administrative, and police positions. The uprising initially broke out in the villages of Doxato, where local Greeks attacked the police station and killed six or seven Bulgarian policemen, and of Prosotsani where the municipality office, the army garrison, and the police station were attacked.

The uprising was "swiftly" and "brutally" suppressed by the Bulgarian occupation authorities. In a few days, by 2 October 1941, almost all the leaders of the various groups were killed. The Bulgarian troops moved into Drama where they arrested all men between the ages of 19 and 45, and into other cities and villages of the region. They commenced reprisals by summarily executing suspects, with Bulgarian military reports listing up to 1,600 Greeks killed in the uprising and in the weeks that followed, while Greek sources claim the dead were in the thousands. The villages of Doxato, Kyrgia, Philiatra, Drymotopos, Kokkinogeia, and Platanovryssi were destroyed and most male inhabitants killed.