Yudhishtra
The eldest of the Pandava brothers, Yudhisthira is their leader as both king and commander in battle. A bad series of dice games he plays lands him, his wife, and his brothers in exile for 13 years, which precipitates a war between the Pandavas and Duryodhana. Yudhisthira is described as living fully by dharma, and in turn always has the gods on his side.
Arjuna
One of the Pandavas brothers, Arjuna is dubbed the "wealth-winner." He is the greatest warrior of all the brothers, having been trained by his future military opponent Drona. Arjuna is a skilled archer and popular with women.
Karna
Karna is technically the oldest of the Pandava brothers, but was raised by adoptive parents, and therefore does not consider himself part of the family. He fights alongside Duryodhana, and is ultimately killed by Arjuna. The Pandavas are devastated to later learn that Karna was one of their own.
Dhritarashtra
The blind king of Hastinapur who believes his blindness is a curse upon him, he gives birth to 100 sons who are demons incarnate. The most powerful of these sons is Duryodhana, who leads the 100 brothers into war against the Pandavas. From early on, Dhritarashtra is well aware that fate is working against Duryodhana, and the blind king pleads with his son over and over to compromise with the Pandavas, lest he violate dharma.
Draupadi
The wife of the five Pandava brothers, Draupadi is a celebrated princess who is widely regarded as the most beautiful woman in the world. During their years in exile, Draupadi must pose as a maidservant and suffer a series of indignities, including an attempted rape by one of Duryodhana's brothers. The humiliation she suffers ends up being one of the causes of the great battle that the Mahabharata revolves around.
Duryodhana
The leader of 100 demon brothers who are all born of the blind king Dhritarashtra, Duryodhana is portrayed as living in flagrant violation of dharma. He is motivated by greed, jealously, and a desire for retribution, tricking Yudhisthira into a dice game that ultimately robs the Pandavas of their kingdom, and gladly engaging them in war when they return from exile and seek what is rightfully theirs. Duryodhana hides in a lake after all his warriors are killed, and is ulimately killed by Bhima. In the afterlife, he resides in hell.
Bhima
The strongest of the Pandavas, Bhima is often the brother who kills the brothers' greatest enemies and protectors them from their most skilled aggressors. Bhima is often described as "wolf-bellied" and is ruthless in acts of violence.
Krsna
The god who assists the Pandavas throughout the story, Krsna helps them understand their dharma as rulers and fighters in the war, and constantly reassures them that any violent act they have trepidation about is mandated by faith. His speech on dharma and action to Arjuna is known as the "Bhagavad Gita," and has been accepted as central to the Hindu tradition alongside the traditional Vedic texts.
Drona
At the time of the story, Drona is an 85-year-old man who fights like a 16-year-old. Even though he fights on behalf of Duryodhana, he shares a close bond with the Pandavas, having trained Arjuna as a warrior. Like many in Duryodhana's army, and unlike Duryodhana himself, Drona is a strict adherent of dharma, and lays down his weapons to accept his death at the Pandava's hand when he violates his dharma on the battlefield.
Vyasa
As depicted in the story, Vyasa is the narrator of the entirety of the Mahabharata epic, dictating the tale to Ganesha. The historical Vyasa is popularly considered to have written the Mahabharata and is considered one of the seven immortal beings in the Hindu tradition.