ISAC may refer to:
internet Speech Audio Codec (as "iSAC"), a wideband speech codec Institute for the Study of American Cultures, a defunct organization devoted to the study of pre-Columbian contact between the Old and New Worlds Institute for the Study of Ancient Cultures, a multidisciplinary research center at the University of Chicago Information Sharing and Analysis Center, a cybersecurity non-profit organization Indian Space Research Organisation Satellite Centre, the lead ISRO centre for technology testing and spacecraft assembly integration in India Immune stimulating antibody conjugate, a monoclonal antibody Idol Star Athletics Championships, Korean biannual Athletics gathering Integrated Sensing And Communication, a 6G wireless network capability
People Isac, variant spelling of Isaac (name) Emil Isac (1886–1954), Romanian poet, dramatist, short story writer and critic Mihaiela Isac, Romanian and Canadian metallurgist Isac Ludo (1894–1973), Romanian writer and political figure Isac Peltz (1899–1980), Romanian prose writer and journalist Isac Silvestre (born 2006), Brazilian football defender
Other Vadul lui Isac is a village in Cahul District, Moldova the Isac is a French river in the Loire-Atlantique department