Agaton Giller (Opatówek, Congress Poland, Russian Empire, 1831 – 1887, Stanisławów, Austro-Hungary) was a Polish historian, journalist and politician.

He and his brother Stefan Giller played notable roles in the Polish independence movement and in the January 1863 Uprising.

After being exiled to Siberia by the Imperial Russian authorities, he became the first Siberian historian and biographer of other deported Poles.

Later, in exile in Paris, he was a journalist with such periodicals as Ojczyzna (The Fatherland) and Kurier Paryski (The Paris Courier), a founder of Polish self-assistance organizations, and a founder of the Polish National Museum in Rapperswil, in Switzerland's Canton of St. Gallen.

The Polish National Alliance, in the United States, considers Agaton Giller its "spiritual father."