The Moirai (also known as the Fates) were the three goddesses of destiny in Greek mythology. They were Clotho, Lachesis and Atropos (Greek: Άτροπος).
The role of the Moirai is to control the fate of every being. The life of each being is represented by a "thread of life". Clotho spins the thread, beginning the being's life. Lachesis measures it (looks how long it is) and Atropos cuts the thread at the end of the person's life once they have reached their destiny, killing them.