Medea was a seer and played a significant role in Greek mythology. Great kings and warriors would go to her to find answers in order to fullfil their destiny (usually related to war)
Medea was considered to be a witch since in Greek mythology she is known to:
Cast spells
Poison her enemies
Make magical beverages oinments
Have Divination abilities (know the future)
Cause sleep (Hypnotism)
Promise immortality through rituals and spells
Use sucrifices especially humans
Have seductive eyes
Brief history
Medea was devoted to Artemis(*) and thought to be the grand daughter of the sun God (Helious, Helios) In her altar she met the mythical hero Jason (Iasonas) who seeked for her help and fell in love with him. She hellped him and betrayed her faith and devotion to her king in order to do so. She poisoned his enemies and they got married secretely.
Hecate (Hekati)
Hecate was considered more of a Godess and less of a witch. However since she had a place in the human world and a physical form she adopted the reputation of a witch from many. Hecate was an only child and she was the daughter of Asteria and the grand daughter of the titan Keos. Zeus respected and loved her greatly so as soon as she was born he offered her part of the sea and land to rule as she wished. The myth states that hecate had great powers over this land and sea. Moreover she had a respectful place in the human world, standing next to great kings and heroes in the court. Also hecate was considered to be a Godess that everyone would pray to and worship even if she had physical form. She would always answer to the prayes of those she was fond of and offer them victory in war and glory in life. Later on Hecate was considered to be the guardian and Godess of magic and Hellenic pagans still pray to her.
Haitis (Aietes)
Haitis was considered to be a wizzard since he was the son of Helious (sun God), father of Medea and uncle of Hecate.
Pasefae
She was considered to be a witch, sister of Haitis, daughter of the sun. She was Mino's wife who was the king of Crete. The myth sais that in order to punish her husbant for being unfaith ful she put a spell on him. Ever since Minos couldn't sleep with any other woman since as the myth goes snakes and scorpios would come out of his body and kill any woman he attempted to sleep with apart from his wife since she was the daughter of the sun. (Her sister Prokris also a witch healed him and married him) In Greek mythology Pasefae fell in love with a taurus (punishment of Venus since she didn't pray enough) and gave birt to the mythical creature minotaur.
Circi
Daughter of the sun, sister of Pasedae and Haitis. In odessey Circi was the evil wsitch that fell in love with Odeseus and wouldn't let him leave her island.
(*) Artemis was the Godess of virginity, child birth and nature. She was devoted to hunt. Daughter of Zeus and Leto twin sister of Apollo. The minute she was borned she helped her mother give birth to apollo since Zeus wife Hera was trying to find her and kill her. The myth sais that she turned her mother into a wolf in order to hide her. She denied love and marriege and was granted eternal virginity.
I thought some may be interested. Personally I think Greek mythology is a piece of art. It's too bad people do not know much about it.