Counterfactual is counterfactual conditional, a conditional containing an if-clause which is contrary to fact.

Counterfactual may also refer to:

• Counterfactual thinking, in psychology
• Counterfactual thought experiments, in philosophy, science, etc.
• Counterfactual history, in historiography
• Alternate history, a literary genre
• Counterfactual subjunctive, grammatical forms which in English are known as the past and pluperfect forms of the English subjunctive mood

• Counterfactual definiteness, in quantum theory
  • Elitzur–Vaidman bomb tester, in quantum theory (counterfactual measurements)