Kostic; in Serbian Cyrillic: ???????? ??????; born 20 March 1952 in Bioska, Užice municipality, Serbia), is a Serbian-American thermodynamicist and professor emeritus of mechanical engineering at Northern Illinois University, Licensed Professional Engineer (PE) in Illinois, and Editor-in-Chief of the Thermodynamics section of the journal Entropy.
He is an expert in energy fundamentals and applications, including nanotechnology, with emphasis on efficiency, efficient energy use and energy conservation, and environment and sustainability.