NISUS, in Greek mythology, king of Megara, brother of Aegeus, king of Athens. When Minos, king of Crete, was on his way to attack Athens to avenge the murder of his son Androgeus, for which Aegeus was directly or indirectly responsible, he laid siege to Megara. He finally gained possession of the city through the treachery of the king's daughter Scylla, who, enamoured of Minos, pulled out the golden (or purple) lock from her father's head, on which his life and the safety of the city depended (for similar stories, see Frazer, Golden Bough, iii. 1900, p. 358). Megara was captured, and Nisus, who died fighting (or slew himself), was changed into a sea-eagle. Minos, disgusted at Scylla's treachery, tied her to the rudder of his ship, and afterwards cast her body ashore on the promontory called after her Scyllaeum; or she threw herself into the sea and swam after Minos, constantly pursued by her father, until at last she was changed into a ciris (a bird or a fish). In Virgil, Scylla, the daughter of Nisus, is confused with the sea-monster, the daughter of Phorcys. Nisus was the eponymous hero of the harbour of Nisaea, and local tradition makes no mention of his betrayal by his daughter. According to Roscher (in his Lexikon der Mythologie), who identifies the ciris with the heron, the story of Nisus and Scylla (like these of Aedon, Procne, Philomela and Tereus) was invented to give an aetiological explanation of the characteristics of certain birds. The birds were regarded as originally human beings, whose acts and characters were supposed to account for certain habits of the birds into which they had been changed. E. Siecke, De Niso et Scylla in aves mutatis (progr. Berlin, 1884), holds that the purple or golden hair of Nisus is the Sun, and Scylla the Moon, and that the origin of the legend is to be looked for in a very ancient myth of the relations between the two, which he endeavours to explain with the aid of Indian and German parallels.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)