These are the five eldest warriors in Kurukshetra war :-
He was elder brother of Shantanu and uncle of Bhishma Pitahma .
He was killed by Bhimasena .
Then Bhima, for Satyaki's sake, afflicted the illustrious Valhika with nine shafts and pierced him therewith at the van of battle. Then the mighty-armed son of Pratipa, Valhika, filled with great fury, hurled a dart at the chest of Bhima, like Purandara himself hurling the thunder. Struck therewith, Bhima trembled (on his car) and swooned away. The mighty warrior then, recovering his senses, hurled a mace at his opponent. Hurled by the son of Pandu, that mace snatched away the head of Valhika, who, thereupon, fell down lifeless on the earth, like a tree struck down by lightning.
He was eldest son of Bahilika and since Bhishma Pitahma was eight child of Shantanu and Mata Ganga , it is very likely he was older than Pitahma .
He was killed by Satyaki .
Then Satyaki, inflamed with rage, aiming at Somadatta's chest, shot a new and terrible Parigha equipped with a golden staff and hard as the thunder. The Kuru warrior, however, smiling the while, cut off that terrible Parigha advancing with speed against him in two parts. That formidable Parigha of iron, then, thus cut off into two fragments, fell down like so many crests of a mountain riven by thunder. Then Satyaki, O king, with a broad-headed arrow, cut off in that encounter Somadatta's bow, and then with five arrows, the leathern fence that cased his fingers. Then, O Bharata, with four other shafts he speedily despatched the four excellent steeds of the Kuru warrior to Yama's presence. And then that tiger among car-warriors with another straight shaft, smiling the while, cut off from his trunk the head of Somadatta's driver. Then he sought at Somadatta himself a terrible shaft of fiery effulgence, whetted on stone, steeped in oil, and equipped with wings of gold. That excellent and fierce shaft, shot by the mighty grandson of Sini, quickly fell like a hawk, O Lord, upon the chest of Somadatta. Deeply pierced by the mighty Satwata, the great car-warrior Somadatta, O monarch, fell down (from his car) and expired.
The great son of Maa Ganga and Shantanu .
He was brought down by Arjuna fairly .
Fierce was the battle fought there between thy troops and those of the enemy on that the tenth day, O king, when Bhishma and Arjuna met together. Like unto the vortex that occurs at the spot where the Ganga meets the Ocean, for a short while a vortex occurred there where the troops of both armies met and struck one another down. And the Earth, wet with gore, assumed a fierce form. And the even and the uneven spots on her surface could no longer be distinguished. Although Bhishma was pierced in all his vital limbs, yet on that the tenth day he stayed (calmly) in battle, having slain ten thousand warriors. Then that great bowman, Partha, stationed at the head of his troops, broke the centre of the Kuru army. Ourselves then, afraid of Kunti's son Dhananjaya having white steeds attached to his car, and afflicted by him with polished weapons, fled away from the battle. The Sauviras, the Kitavas, the Easterners, the Westerners, the Northerners, the Malavas, the Abhishahas, the Surasenas, the Sivis, the Vasatis, the Salwas, the Sayas, the Trigartas, the Amvashthas, and the Kaikeyas-these and many other illustrious warriors,--afflicted with arrows and pained by their wounds, abandoned Bhishma in that battle while he was fighting with the diadem-decked (Arjuna). Then a great many warriors, surrounding that single warrior on all sides, defeated the Kurus (that protected him) and covered him with shower of arrows. Throw down, Seize, Fight, Cut into pieces,--this was the furious uproar, O king, heard in the vicinity of Bhishma's car. Having slain in that battle, O monarch, (his foes) by hundreds and thousands, there was not in Bhishma's body space of even two fingers' breadth that was not pierced with arrows. Thus was thy sire mangled with arrows of keen points by Phalguni in that battle. And then he fell down from his car with his head to the east, a little before sunset, in the very sight of thy sons. And while Bhishma fell, loud cries of alas and oh, O Bharata, were heard in the welkin uttered by the celestials and the kings of the earth. And beholding the high-souled grandsire falling down (from his car), the hearts of all of us fell with him. That foremost of all bowmen, that mighty-armed hero, fell down, like an uprooted standard of Indra, making the earth tremble the while.Pierced all over with arrows, his body touched not the ground. At that moment, O bull of Bharata's race, a divine nature took possession of that great bowman lying on a bed of arrows. The clouds poured a (cool) shower (over him) and the Earth trembled. While falling he had marked that the Sun was then in the southern solstice.
He was son of Bharadwaj and is the only one with a clear age in Mahabharata which was supposed to 405 years .
He was slain by Drishtadyumna unfairly .
Thus addressed by Bhima, the mighty-armed Dhrishtadyumna speedily took up a strong, a new and a superb bow capable of bearing a great strain. Filled with rage, and shooting his arrows in that battle at the irresistible Drona, Dhrishtadyumna covered the preceptor, desirous of withstanding him. Those two ornaments of battle then, both foremost of fighters and both filled with rage, invoked into existence the Brahma and diverse other celestial weapons. Indeed, O king, Dhrishtadyumna covered Drona with many mighty weapons in that encounter. Destroying all the weapons of Bharadwaja's son, the Panchala prince, that warrior of unfading glory, began to slay the Vasatis, the Sivis, the Valhikas and the Kurus, that is, them, who protected Drona in that battle. Indeed, O king, shooting showers of arrows on all sides, Dhrishtadyumna at that time looked resplendent like the sun himself shedding his thousands of rays. Drona, however, once more cut off the prince's bow and pierced the vitals of the prince himself with many arrows. Thus pierced, the prince felt great pain. Then Bhima, of great wrath, holding the car of Drona, O monarch, slowly said these words unto him: If wretches amongst Brahmanas, discontented with the avocations of their own order, but well-versed in arms, did not fight, the Kshatriya order then would not have been thus exterminated. Abstention from injury to all creatures hath been said to be the highest of all virtues. The Brahmana is the root of that virtue. As regards thyself, again, thou art the foremost of all persons acquainted with Brahma. Slaying all those Mlecchas and other warriors, who, however, are all engaged in the proper avocations of their order, moved thereto by ignorance and folly, O Brahmana, and by the desire of wealth for benefiting sons and wives; indeed, for the sake of an only son, why dost thou not feel ashamed? He for whom thou hast taken up weapons, and for whom thou livest, he, deprived of life, lieth today on the field of battle, unknown to thee and behind thy back. King Yudhishthira the just hath told thee this. It behoveth thee not to doubt this fact.' Thus addressed by Bhima, Drona laid aside his bow. Desirous of laying aside all his weapons also, Bharadwaja's son of virtuous soul said aloud, 'O Karna, Karna, O great bowman, O Kripa, O Duryodhana, I tell you repeatedly, exert yourselves carefully in battle. Let no injury happen to you from the Pandayas. As regards myself, I lay aside my weapons.' Saying these words, he began loudly to take the name of Aswatthaman. Laying aside his weapons then in that battle, and sitting down on the terrace of his car, he devoted himself to Yoga and assured all creatures, dispelling their fears. Beholding that opportunity, Dhrishtadyumna mustered all his energy. Laying down on the car his formidable bow, with arrow fixed on the bow-string, he took up a sword, and jumping down from his vehicle, rushed quickly against Drona. All creatures, human beings and others, uttered exclamation of woe, beholding Drona thus brought under Dhrishtadyumna's power. Loud cries of Oh and Alas were uttered, as also those of Oh and Fie. As regards Drona himself, that large head of Bharadwaja's son before the warriors of thy army. Thy soldiers, O monarch, beholding the head of Bharadwaja's son, set their hearts on flight and ran away in all directions. Meanwhile Drona, ascending the skies, entered the stellar path. Through the grace of the Rishis Krishna (Dwaipayana), the son of Satyavati, I witnessed, O king, the (true circumstances about the) death of Drona. I beheld that illustrious one proceeding, after he had ascended the sky, like a smokeless brand of blazing splendour. Upon the fall of Drona, the Kurus, the Pandavas and the Srinjayas, all became cheerless and ran away with great speed. The army then broke up. Many had been slain, and many wounded by means of keen shafts. Thy warriors (in particular), upon the fall of Drona, seemed to be deprived of life. Having sustained a defeat, and being inspired with fear about the future, the Kurus regarded themselves deprived of both the worlds. Indeed, they lost all self-control. Searching for the body of Bharadwaja's, son, O monarch, on the field covered with thousands of headless trunks, the kings could not find it. The Pandavas, having gained the victory and great prospects of renown in the future, began to make loud sounds with their arrows and conchs and uttered loud leonine roars. Then Bhimasena, O king, and Dhrishtadyumna, the son of Prishata, were seen in the midst of the (Pandava) host to embrace each other. Addressing the son of Prishata, that scorcher of foes, viz., Bhima said, 'I will again embrace thee, O son of Prishata, as one crowned with victory, when that wretch of a Suta's son shall be slain in battle, as also that other wretch, viz., Duryodhana.' Having said these words, Bhimasena, the son of Pandu, filled with transports of joy, caused the earth to tremble with slaps on his armpits. Terrified by that sound, thy troops ran away from battle, forgetting the duties of the Kshatriyas and setting their hearts on flight. The Pandavas, having become victors, became very glad, O monarch, and they felt great happiness, derived from the destruction of their foes in battle .
He and his twin sister were children of Maharishi Sharavadat Gautam .
He was one of the few survivors of wars .
Having said these words unto the king deprived of his senses and lying with broken thighs, Ashvatthama once more cast his eyes on him and uttered these words, "If, O Duryodhana, thou hast any life in thee still, listen to these words that are so pleasant to hear. On the side of the Pandavas, only seven are alive, and among the Dhartarashtras, only we three! The seven on their side are the five brothers and Vasudeva and Satyaki; on our side, we three are myself and Kripa and Kritavarma! All the sons of Draupadi have been slain, as also all the children of Dhrishtadyumna! All the Pancalas too have been slain, as also the remnant of the Matsyas, O Bharata! Behold the vengeance taken for what they had done! The Pandavas are now childless! While buried in sleep, the men and animals in their camp have all been slain! Penetrating into their camp in the night, O king, I have slain Dhrishtadyumna, that wight of sinful deeds, as one kills an animal.
Then there are some other such as Drupada who was classmate of Drona , Shalya who was present in Kashi Swayamvara were Bhishma had fought him , Bhagdutta was supposed to be very old , Bhurishava was very old too .
Jai Sri Krishna .
