In Greek mythology, Arctus () was the twelfth Hora (Hour) who presided over the night sky and constellations. She was originally not part of this lesser-known group of goddesses.
Arctus was sister of the other eleven Horae: Auge (First Light), Anatole (Sunrise), Musica (Hour of Music), Gymnastica (Hour of Exercise), Nymphe (Hour of Bath), Mesembria (Noon), Sponde (Libation), Elete (Hour of Prayer), Acte (Hour of Pleasure), Hesperis (Evening), and Dysis (Sunset).
Their father was said to be either Helios (the Sun god) or Chronos, (the personification of Time).
Arktos along with her sisters, Antolia, Dysis and Mesembria, attended of the goddess Harmonia (Harmony) within her halls in heaven. Like of her siblings, she guarded one of the four gates of the Winds.