Inconstant Moon is a science fiction short story collection by American author Larry Niven that was published in 1973. "Inconstant Moon" is also a 1971 short story that is included in the collection. The title refers to "O, swear not by the moon, th' inconstant moon", a quote from the balcony scene in William Shakespeare's Romeo and Juliet. The collection was assembled from the US collections and All the Myriad Ways.