Here is a basic idea of how the charactors look like. It's taken from serial Mahabharata from starplus. I got all the images from Google.
Lord shreekrisna. Also known as Krishn vashudev.
Bhagban balram. Or baldau. Elder brother to krishn vashudev.
Subhadra. Younger sister to both krishn and balram. Later married to the mighty Archer Arjun.
Mata kunti. Mother of pandavas.
Pitamah bhisma. Grandfather of pandavas and kouravas.
Dhritarastra king of Hastinapur and father of kouravas.
Mata gandhari mother of kouravas and Queen of Hastinapur.
Vidur. Chief minister of Hastinapur. Younger brother to king. Uncle to pandavas and kouravas.
Shakuni. King of Gandhar. Brother of queen gandhari. The bad guy.
Dronacharya. Teacher of pandavas and kouravas.
Aswasthama. Son of dronacharya. Friend of kouravas.
Duryadhana. Eldest kourava.
Dishasan. Second kourav.
Yudhistir. Eldest in both pandavas as well as kouravas.
Bheem. Second pandavas. Known for his physical strength.
Arjun. Third pandav. Known for being the great Archer and an amazing worrior.
Nakul. 4th pandav. Being a great charioteer and sword fighter. Known for his beauty. Consider as the most handsome man of his time.
Sahadev. Last pandav. Known for his knowledge and foresight.
Karn. Hidden son of kunti. Always compitative to Arjun. As he was a great Archer too.