Where to begin! There are very many similarities between Norse and Greek and Roman Mythology, but one of the biggest differences involves the female gods. In Greek and Roman Mythology, there are only five very important goddesses. In Norse Mythology, there are 20 major goddesses. This could be attributed to the fact that Norse Mythology has around 52 major gods and goddesses. That's only the goddesses though, as there are so many more levels of females with Godly abilities in Norse Mythology. First off, Norse Mythology originated among the Swedes, Danes, and Norwegians between 780 and 1070 AD, a far cry from Greek and Roman Mythology which began some time around the 8th Century BC. You'll learn, from the list below, that messing with a Norse goddess would not be the smartest thing to do.
We'll start with Frigg, the highest ranking of the Norse goddesses, and the wife of Odin (the Zeus of Norse Mythology). She knows what her husband Odin does about humanities destiny in Ragnarok, but tells no one. She is associated with childbirth and it is because of her role as a goddess of fertility that most tend to view her as promiscuous. She is the mother of Baldur the Good, who, fearing for his life, exacted an oath from fire, water, all the metals, stones, trees, diseases, animals, poisons and everything else, so that none of them would do harm to her son. Unfortunately, she did not ask for the Mistletoe's word, believing it too young and feeble to take an oath from. The mistletoe, thanks to the helping hands of the Trickster God Loki, killed Baldur. With the role as the grieving mother of a murdered son, Frigg is connected with the Virgin Mary. Her symbol is that of the fish, which gives her ties to another goddess of fertility, Aphrodite. The word Friday' come from Frigg as well, "Frigg's Day."
Freya, not to be confused with her husband Freyr, is a goddess among the Earth-based deities, as apposed to the sky-based ones, like Frigg and Odin. She is married to her brother, Freyr, a fertility god himself, and inhibits magic of productivity, the phenomenon of sexuality and the gift of child birth. Her many sexual liaisons help to belay the fact that she has a fertility aspect to herself as well. Odin was known to lust after her because of her incredible beauty and she is thus, at times, confused with the goddess Frigg. She is known well as the goddess of war and love, and at times gave sexual favors in order to get things that she desired.
The goddess Sif was the wife of Thor, one of Odin's many sons, and god of Thunder. Like Frigg, Freya and Freyr, Sif was a Goddess known for fertility, and was renowned for her beauty and wheat-like hair. One night, while Sif slept beside her husband, that trickster god Loki shaved off her beloved hair. Enraged, Thor caught Loki by his neck and threatened to kill him, and Loki swears he can replace it. Loki convinces the dwarves, master metal smiths, to spin a headpiece known as the "Sons of Ivaldi".
Nott, or Night, was the daughter of a Giant named Norfi. Taking after her name, Nott was known to have long dark hair. She was married three times, and had one child with each husband. Her first child was a son named Auor. Her second child Giant Jord, or Earth and last she had another son, named Dagur, or Day. As Odin was making the world, he took Nott and Dagur and put them in the sky with chariots to ride around the world for twenty-four hours.
Nott's second child, Jord, was the embodiment of Earth. She also became one of Odin's concubines and bore him one son; Thor. Upon her relations with Odin, she too became a goddess. Not much else is known of Jord.
The gods are not immortal, and much like the Greek gods ate Ambrosia to retain their immortality, the gods and goddesses of Norse Mythology ate apples grown by the goddess Idunn to keep them youthful. She is kidnaped by a Giant with Loki's help, and when the gods in Asgard begin to age, the force Loki into rescuing her. It's unknown if Idunn had a brother, but there are whispers he was killed by Loki somewhere along the way. They also say that she may have had sexual relations with said killer.
Before his death, Baldur had a wife by the name of Nanna. She bore him a son, Forseti, the god of Justice. It is said that when Baldur died, her heart broke and she died as well. She was placed along side her husband on his funeral pyre and they were burned together.
The Valkyrie's were armed and mounted, warlike virgins, usually daughters of gods, and Odin's messengers. They selected slain heroes for Valhalla and serve them as their feasts. Odin will use both the Valkyrie and dead heroes when Ragnarok occurs. Valkyrie literally means, "Choosers of the slain." When they rode out to find and pick fallen warriors, their shields would glint in the Northern sky, and people named this the "Aurora Borealis."
Like in Greek and Roman Mythology, Norse Mythology has it's own trio of fate sisters. In Greek Mythology, they're known as the Moirae Clotho (thread of life), Lachesis (length of thread), and Atropos (cutter of thread). In Roman Mythology, they were called the Parcae Nona (thread of life), Decima (length of thread), and Morta (cutter of thread). In Norse Mythology, the sisters were known as the Norns:
The eldest Norn was Urdur, who knew of a persons the past.
After Urdur was Verdandi, who controlled their present.
The youngest sister was Skuld, who prepared the future and was also a Valkyrie.
All three tended to the roots of the great Yggdrasill tree, which linked the three words together, from Hel, to Midgard, to Asgard.
Speaking of Hel, she was the daughter of Loki and ruler of the realm known as Hel (Niflheim), the land of the dead for those that don't die gloriously in battle. From the waist up, Hel appeared alive and well, but from the waist down, her flesh was rotting and dead. She agreed to return Baldur back to the land of the Asgard if every living thing in every realm wept for him.
Hel's mother was a Giantess by the name of Angrboda. Angrboda, with Loki, bore children most foul to the world: The Giant Wolf, Fenrir, the Midgard Serpant, Jormungandr, and Hel.
Loki's other wife was named Sigyn. When Loki was captured for the murder of Baldur, it was Sigyn that stood by his side. They tied Loki to three rocks, and hung snakes over his head so that the poison from their fangs would drip into his eyes. Sigyn, stayed with him, and held a bowl to catch the poison drops. Unfortunately, when the bowl fills, Sigyn must leave, and when the poison hits Loki, he shakes in pain and causes earthquakes.
So many goddesses and so little time they had, compared to the goddesses of Greek and Roman Myth. The women in Norse Mythology were tough, and many. They range the spectrum of female emotions and stories. Fertility was a major among the most powerful of goddesses, as well as beauty. Sex wasn't a special thing, instead a device to get what one wanted or just to have sex. Infidelity was common among both the gods and goddesses, so it was rare to see loyalty like that of the Giantess Sigyn. Perhaps because she wasn't a goddess, she was so loyal to her horror of a husband. They tended to stay out of the boys games, plans and fights, which were many. Rarely do you read about goddesses getting involved in battles, not until Ragnarok, when they will be forced to take part.