Cainan can refer to either:
- Cainan, the son of Enos, as mentioned in the Gospel of Luke, 3.37 and the Septuagint. It is a variant of the name Kenan in the generations of Adam, the lists of antediluvian patriarchs given in the Torah;
- Cainan, the son of the Arpachshad mentioned in most manuscripts of the Gospel of Luke 3:36. This reference to Cainan is present in the Septuagint and Samaritan versions of the Book of Genesis, as well as in the Book of Jubilees. Early Christian apologists Irenaeus and Eusebius believed his presence to be an error mainly on the basis of his omission from the Masoretic (Hebrew) version and many subsequent interpreters followed this. However Helen Jacobus has argued that the omission from the Masoretic text is deliberate. 
According to the Book of Jubilees, Cainan was taught to read by his father, and he found, carved on the rocks by former generations, an inscription preserving the science of astrology as taught by the Watchers, who had rebelled from God before the deluge. He is also stated to have married a daughter of Madai named Melka.
In The Patriarchal Age: or, the History and Religion of Mankind (1854), George Smith writes:
- "It is remarkable that, notwithstanding the omission of the name of Cainan from the Hebrew text, and the consequent general rejection of him by historians, there are more traditions preserved of him than of his son Salah. 'The Alexandrine Chronicle derives the Samaritans from Cainan*; Eustachius Antiochenus, the Saggodians; George Syncellus, the Gaspheni; Epiphanius the Cajani. Besides the particulars already mentioned, it is said Cainan was the first after the flood who invented astronomy, and that his sons made a god of him, and worshiped his image after his death. The founding of the city of Harran in Mesopotamia is also attributed to him; which, it is pretended, is so called from a son he had of that name.' -Anc. Univ. Hist., vol. i, p. 96, note."
(* What the Latin Alexandrine Chronicle actually says is that "those who live east of the Sarmatians" were derived from Cainan)