In Goidelic mythology, Cian was the father of Lugh by Ethlinn and a member of the Tuatha de Danaan.

According to a prophecy, Balor, the god of the underworld was to be killed by his grandson. He locked his daughter, Ethlinn, in a tower made of crystal to keep her from becoming pregnant. However, Cian, with the help of the druidess Birog, managed to enter the tower. Ethlinn soon gave birth to Lugh, a son of Cian. Balor then threw Lugh into the ocean, but Lugh was saved by Birog and became the foster son of Manannan mac Lir.

It is also an Iranian name. In Persian Kian means "generations".