ICOS (disambiguation)

ICOS was an American biotechnology company.

ICOS may also refer to:
 * ICOS (gene), a gene which encodes the protein CD278
 * Integrated Carbon Observation System, a research infrastructure
 * Integrated cavity output spectroscopy, a type of laser absorption spectrometry
 * International Council of Onomastic Sciences, an academic organization
 * The International Council on Security and Development, an international think tank
 * Irish Co-operative Organisation Society, a business association