Adam Franciszek Józef Siedlecki or Adam Grzymała-Siedlecki (AGS) (1876–1967) was a Polish literary and theater critic, playwright, translator, prose writer and director.

Juliusz Słowacki Theatre is a 19th-century Eclectic theatre-opera house in the heart of Kraków, Poland, and a UNESCO World Heritage Site. Erected in 1893, it was modeled after some of the best European Baroque and Eclectic theatres such as the Palais Garnier in Paris. The theatre was named after Polish poet Juliusz Słowacki in 1909 and in 1978 was inscribed alongside the Historic Centre of Kraków into the World Heritage Register.