In Egyptian religion, Hathor was a predynastic goddess who embodied femininity, love and the joy of motherhood. In addition to being a symbol of fertility, she was known as a goddess of the underworld, in that she welcomed the newly departed to the West. According to the Enclyclopedia of World Myth, Hathor's cult developed first as a cow cult, and then advanced to become a worship system based upon fertility and fecundity. Hathor was extremely popular in Egypt, and many children were named for her.
Hathor is represented by the cow, and is typically portrayed with a pair of horns on her head, as well as a solar disc. In many cases, she appears with a crown of serpents, which represents wisdom. Egyptian relationships are complex, especially when it comes to the family trees of the gods, and she is sometimes identified as the mother, sister, or wife of Ra. In some stories, it is she and not Isis who is the mother of Horus.
Among her many titles, Hathor is known as Lady of the House of Jubilation, indicating her position as a goddess of joy. She was venerated by women specifically, although both men and women worked as priests in her temples.
In one legend, Hathor becomes angry with Ra, and decides to leave Egypt. The land falls into mourning, and Ra decides that Hathor needs to come back to help liven things back up. While she's out wandering around in a rage, Hathor turns into a wild cat, deadly and destructive towards anyone and anything that gets close, so really, no one wants to take on the task of going and collecting her back home. Finally, Thoth, the god of wisdom, gives in and goes (in disguise) to get Hathor. He coaxes her back to Egypt, where she bathes in the waters of the Nile and calms down a bit. As she does so, the waters turn red from soothing Hathor's anger.
Hathor was honored for some two thousand years in Egypt, before being absorbed into the aspect of Isis. In Greek culture, Hathor was seen as Aphrodite, and the two share some similar characteristics.