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 The Shape of Space and All the Myriad Ways.

Laurence van Cott Niven is an American science fiction writer. His 1970 novel Ringworld won the Hugo, Locus, Ditmar, and Nebula awards. With Jerry Pournelle he wrote The Mote in God's Eye (1974) and Lucifer's Hammer (1977). The Science Fiction and Fantasy Writers of America gave him the 2015 Damon Knight Memorial Grand Master Award.