Rakshasas are troll-like beings who posses what we in modern terms would call mystic powers. In their natural appearance, they look ugly and fearsome with long protruding fangs, and stiff hairs on their body. But they have the yogic powers to change shape, or assume any form they like.
For instance, a female Rakshasa, Hidimbi, was so captivated by Bhimasena that she appeared before him as a most beautiful women. They even married and had a son named Ghatotkach. Ghatotkach became a mighty, fearsome warrior, who played an important role in the battle of Kurukshetra.
Rakshasas’ favorite food is human blood, and their powers increase after sunset.
My personal speculation is that Bram Stoker was actually inspired by the Rakshasas of the Vedic tradition, when he created the legend of Dracula.
Below, I have reproduced a section from Mahabharata, as it has been retold by Krishna Dharma Das of ISKCON.
Arjuna looked across at Karna. He longed for the moment when he would be able to curb his pride once and for all. The Pandava knew about his Shakti weapon, but it did not bother him. He had faced every kind of celestial missile before in battle. Krishna's infallible advice, however, should be followed.
Perhaps the Shakti was more powerful than he thought. Arjuna summoned Ghatotkacha and the Rakshasa soon appeared before him, encased in armor and ready with bow and sword. Offering obeisances before both Krishna and Arjuna, he said, "Here I am, O rulers of men. Please order me."
Krishna replied, "Take my blessings, O Ghatotkacha, and hear what must be done. The hour for you to display your prowess has arrived. I do not see another who can accomplish what you can do. Over there stands the powerful Karna, hurling his weapons and scorching our army. None can stand before him but you.
Therefore, become the raft which will carry us across the frightful Kaurava ocean, where Karna is its shark. Rescue your fathers and uncles, for this is the reason why a man begets sons. You are indeed a worthy son of Bhima, O Rakshasa, as you always desire his welfare. Use your illusions and power to check the fierce bowman Karna. Pandu's sons, headed by Dhristadyumna, will engage with Drona and his forces."
Arjuna told Ghatotkacha that he would send Satyaki to protect him from other attacks as he fought with Karna. He should simply concentrate all his power on the suta's son and his followers.
Ghatotkacha was overjoyed at the opportunity to serve his uncle and Krishna. "I am up to this task, O Bharata. I am surely a match for Karna and any other powerful hero who cares to face me. As long as the world exists, men will speak of the battle I will fight tonight. Fighting in the Rakshasa mode, I will spare no one, even those who solicit mercy with folded palms."
Bowing again before Arjuna and Krishna, Ghatotkacha then left and rushed toward Karna. He launched flaming arrows at him from a distance of two miles and bellowed out his challenge. Seeing the huge Rakshasa bearing down upon him, Karna stopped slaughtering the Pandava troops and turned to face him. As a violent encounter took place, Alambusha approached Duryodhana and said, "Permit me to engage with the Pandavas, O King.
I desire to slay them and offer their blood as an oblation to my deceased relatives. By some Rakshasa-killing charm they managed to kill my brother Baka and my father Jatasura, but they will not escape me, for this night hour has doubled my power."
Duryodhana smiled at the Rakshasa. "Go and challenge Ghatotkacha. He is of your race and is waging a terrible battle with Karna. Ever devoted to the interests of the Pandavas, he is creating carnage among my troops."
Alambusha looked across at Ghatotkacha and licked his lips. "I go at once." He mounted his iron chariot with its spikes protruding from the sides and, uttering a deafening roar, charged.
Ghatotkacha, screaming hideously, maintained an unending assault on Karna and, at the same time, destroyed thousands of the warriors who supported him. As Alambusha came at him, he laughed and released a powerful volley of long iron shafts with flaming points. The scorching arrows struck Alambusha and checked his progress. Employing his Rakshasa powers, Ghatotkacha then caused a tremendous downpour of shafts to appear on the battlefield. They fell on Karna, Alambusha, and all the Kauravas surrounding them.
Alambusha displayed similar skills to produce arrows which countered those of his foe. For some time the two Rakshasas fought, both exhibiting mystical illusions. Flaming rocks and lances fell from the sky. Ferocious beasts and ghastly-looking wraiths and spirits rose from the ground; their screams terrified the Kaurava soldiers who ran in fear. Even in the dark of night, an even denser darkness suddenly set in, making everything invisible.
As one Rakshasa created an illusion, the other countered it with his own power. They fired countless arrows at one another and hurled darts, maces, iron balls, axes and lances. They roared in fury, making the earth vibrate. Ghatotkacha succeeded in smashing his opponent's chariot with a number of steel shafts shot in swift succession.
Alambusha leapt down and flew at Ghatotkacha with outstretched arms. He struck his antagonist with his bare fists, and Ghatotkacha shook like a mountain in an earthquake. Raising his own bludgeon-like arm, he dealt a crushing blow to Alambusha that sent him sprawling. Ghatotkacha jumped onto his foe and pressed his neck, but Alambusha wrestled himself free.
The two Rakshasas fought hand to hand as the hair of onlookers stood erect in fear. Striking and kicking, they threw each other to the ground. Both changed shapes––one becoming a great serpent and the other an eagle, one an elephant and the other a tiger, then a pair of sharabhas. Rising into the sky, they appeared like two planets colliding. They fought wonderfully, attacking each other with mallets, swords, spears, trees and mountain peaks.
Gradually, Ghatotkacha's superior strength began to tell. Seeing Alambusha tiring, he seized him by the hair. He dashed him to the ground and dealt him a great kick. Taking hold of a shining scimitar, he jerked his head upwards and severed it from his trunk. Ghatotkacha got onto his chariot still holding the head. He went over to Duryodhana and tossed it into his chariot. Seeing the blood-soaked head, its face contorted and hair disheveled, Duryodhana was shocked.
He looked over at Ghatotkacha, who shouted, "Just see your friend, O King, whose great prowess you have personally witnessed. You are destined to see Karna and indeed yourself meet a similar end. The scriptures say that one should never go before a king with empty hands. Accept, then, this head as my gift to you. Be free from anxiety only for as long as I do not slay Karna."
Ghatotkacha turned away from Duryodhana and resumed his attack on Karna, who was hemmed in by Pandava warriors striving to hold him in check. The Rakshasa sent a stream of shafts at Karna and the fight between them carried on in earnest. Like two tigers tearing each other with their claws, they mangled each other with their lances, arrows and darts. Their blazing shafts lit up the battlefield.
No one could look at them as they released their weapons. Covered with wounds and steeped in their own blood, they resembled two hills of red chalk with rivulets flowing down their sides. Even though both were endeavoring to their utmost, they could not make the other flinch. The twang of their bows filled the four quarters like the continuous rumbling of thunder.
Realizing that he could not overpower his foe with arrows, Ghatotkacha invoked the Rakshasa weapon. Karna was immediately encircled by a force of demons armed with large rocks, lances, trees and clubs. Other Rakshasas appeared in the sky and rained down an incessant shower of javelins, battle-axes and iron wheels on Karna and the Kaurava army. Everyone fled in alarm. Only Karna, proud of his strength, did not flee.
With tens of thousands of arrows he checked the Rakshasa illusions and countered their weapons. Ghatotkacha rushed at Karna with his mace whirling above his head. Karna cut the mace apart with a dozen arrows and pierced his chest with twenty more. Stopped in his tracks, Ghatotkacha hurled at Karna a razor-edged discus adorned with jewels and shining brilliantly. Karna again cut the weapon to pieces almost as soon as it left the Rakshasa's hand.
Seeing his discus fall in fragments, Ghatotkacha blazed up in anger and covered Karna with arrows as Rahu covers the sun. Karna countered his attack and sent a similar number of shafts at his foe. Ghatotkacha rose into the sky and soared above Karna's head. He dropped rocks and trees on him by the hundreds, but Karna smashed them to pieces with his arrows. Invoking a celestial weapon, Karna pierced Ghatotkacha all over his body with so many arrows that he appeared like a porcupine with erect quills.
Ghatotkacha used his own illusory powers to counter Karna's weapon, then disappeared from view. Suddenly, showers of arrows began to appear from all parts of the sky and from every quarter. They fell upon the Kauravas and Karna from all sides. Karna invoked other divine weapons, but Ghatotkacha appeared in a form with many huge heads and swallowed them.
He ranged about the heavens and on the ground, seeming to be in many places at once. At one moment he was seen in a vast form and in the next he was as small as a thumb. He entered the earth and went high into the sky. Appearing at a great distance, he suddenly reappeared right next to Karna.
Ghatotkacha created a mountain on the battlefield which issued forth a shower of weapons. Karna, unruffled, broke the mountain to pieces by means of a celestial missile. The Rakshasa then created a dense blue cloud above Karna that dropped a thick shower of boulders. Karna blew the cloud away with the Vayavya weapon. With limitless arrows, he continuously destroyed the Rakshasa illusions.
Thousands of demons then attacked Karna with every kind of deadly weapon. Karna checked all his attackers with swift shafts shot with such speed that they could not be seen until they struck their target. The afflicted Rakshasa forces appeared like a host of wild elephants assailed by an angry lion. Karna destroyed them like the god of fire burning down all creatures at the end of creation. Only Ghatotkacha could stand before the enraged Karna as he released his weapons.
Bhima's son then created a chariot created by his own powers of illusion. The chariot resembled a hill and was yoked to a hundred goblin-headed asses as big as elephants. They drew Ghatotkacha close to Karna, and the Rakshasa hurled a celestial lance at him that blazed through the sky like a lightning bolt. Amazing all the onlookers, Karna caught the lance and threw it back at Ghatotkacha.
The surprised Rakshasa leapt clear and the lance hit his chariot, smashing it into a thousand flaming pieces and killing its horses and charioteer. As his chariot exploded, Ghatotkacha rose again into the sky. Karna directed numerous celestial weapons at him, but he avoided them all by his agility and illusory powers.
He multiplied himself into a hundred forms so that Karna could not distinguish which of them was actually his enemy. Then he made ferocious animals appear from all directions. Lions, tigers, hyenas, fire-tongued snakes and iron-beaked vultures issued forth and ran screaming or roaring at Karna and the other Kauravas.
Packs of wolves and leopards with gruesome features rushed across the field, along with numerous ghosts, pishachas, jinn and men with beasts' heads. Karna remained steadfast on his chariot and struck all the creatures with straight-flying shafts. Uttering incantations sacred to the sun-god, he burned up his assailants by the tens of thousands. Struck by Karna's mantra-charged arrows, their bodies fell to the earth in charred and mutilated pieces.
Ghatotkacha vanished from sight and boomed out at Karna from across the sky, "Your end is near, wretch. Wait and I will slay you."
Karna, unable to see his opponent, covered the sky with arrows. Suddenly, a great red cloud appeared in the heavens, casting a red glow over the battlefield. It emitted flashes of lightning and tongues of fire. The cloud roared as if thousands of drums were being beaten simultaneously. From it fell countless gold-winged shafts, spears, heavy clubs, spiked bludgeons, razor-edged discuses and numerous other weapons. They dropped on the surviving Kauravas, who wailed in distress.
From out of the cloud flew thousands of Rakshasas clutching spears and battle-axes. They ranged about the sky like flying mountains. With blazing faces and sharp teeth, the monstrous demons struck terror into the Kauravas' hearts. Descending onto the battlefield, they slaughtered Duryodhana's forces without mercy. A confused din arose in the gloom of the night battle as thousands of brave warriors lost their lives. Unable to stand against their attackers, the Kauravas fled. As they ran they cried, "Run! All is lost! The gods with Indra at their head have come to destroy us."
Karna alone, covered by arrows, remained fearless. He fought back against the Rakshasas, warding off their attack and sending his blazing steel shafts into the sky and in all directions. Closing on his intrepid foe, Ghatotkacha hurled four irresistible lances that slew Karna's horses. Karna saw him swiftly approaching, his scimitar held high. All around him he heard the Kauravas' wails and cries: "O Karna, use Indra's weapon to slay this colossus. Otherwise, he will kill us all with his mighty illusions."
Karna reflected. There was no alternative. The Rakshasa was consuming all his celestial weapons. Nothing could stop him except the infallible Shakti. Seeing that Gatotkacha would also slay him, he forgot about Arjuna and snatched the Shakti weapon from its gold case. Placing it on his bow he aimed it at the Rakshasa while uttering the mantras.
The battlefield around him became brilliantly illuminated, as if the sun had risen. Fearful winds blew and thunder resounded in the heavens. Karna released the weapon and it flew like a fireball at Ghatotkacha. The Rakshasa saw his end approaching and suddenly expanded his body to an immense size. Towering above the battlefield, he was struck full on the chest by the Shakti. It passed clean through his body and flew up into the sky, disappearing into the heavens to return to Indra.
Slain instantly, Ghatotkacha fell toward the Kauravas. His huge frame crushed a complete division of warriors as he hit the ground. As he died, his frightful illusions vanished. Seeing his opponent killed, Karna roared with joy. Duryodhana and his brothers shouted with him and the Kauravas beat drums and blew conches. They surrounded Karna and praised him with cheerful voices.