Red bug may refer to:

• Tegastes acroporanus a coral parasite, known in the reef-keeping hobby as "red bugs"
• Red Bug, North Carolina
• Auto Red Bug, an automobile manufactured 1916-1920 by the American Motor Vehicle Company in Lafayette, Indiana
• Pyrrhocoridae, a family of insects
• Smith Flyer, an automobile manufactured 1915-1919 by the A.O. Smith Company in Milwaukee, Wisconsin
• Trombicula, a genus of harvest mites

• Cardin, OK
• Cardin, Oklahoma
• Cardinorm
• Cardio
• Cardiobacteriaceae
• Cardiobacteriales
• Cardiofaciocutaneous Syndrome
• Cardiofaciocutaneous syndrome
• Cardiogenic shock
• Cardioid
• Cardioid article proofs
• Cardioid/Proofs
• Cardiolipin
• Cardiologist
• Cardiology
• Cardiology diagnostic tests and procedures
• Cardiomyocyte
• Cardiomyopathy
• Cardiopulmonary bypass
• Cardiopulmonary receptors
• Cardio-pulmonary resuscitation
• Cardiopulmonary resuscitation
• Cardiothoracic surgery
• Cardio-thoracic surgery
• Cardiotocograph