Q might refer to:
- Q is the seventeenth letter in the English alphabet. It is fairly unique in that most other languages do not have a letter for the English "qu" (though the letter "q" is often used in transliterations, especially of Arabic languages).
- The Q gospel is a hypothesized collection of sayings of Jesus (from the German Quelle, meaning source).
- Q is an incredibly large unit of energy that is used to measure the amount of energy output on a planetary scale using convenient numbers. 1 Q is equivalent to 1.05 x1021 joules. Around the time the anthropogenic activity starts consuming 1 Q of energy, it will produce enough direct heat (i.e., not due to the greenhouse effect) to raise the global temperature by 1 °C.
- The Q are a race of nigh-omnipotent beings from Star Trek. Thanks to the wonders of narrativium, stuff like the omnipotence paradox or the ability of the Q to just slag everything in sight were never much of a problem, although their gadgets in the James Bond films were pretty cool.