CYC or Cyc may refer to:

• Cycle gene, a circadian control gene found in Drosophila melanogaster responsible for the formation of the formation of CYC protein

• Cyc, an American artificial-intelligence project

• Champions Youth Cup, an annual international youth football (soccer) tournament

• China Youth Corps, a Taiwanese youth organization

• Company of Young Canadians, a Canadian youth program

• Cyclorama (theater), a curved fabric or plastic sheet backdrop for a stage

• Cycnoches, a genus of orchid

• Cytochrome c, a protein of the mitochondrial electron transport chain

• Cyclophosphamide, an anti-neoplastic and immunosuppressant drug