Mahisha was a leader or king in the Danava clan of Asuras. He was killed by Mahasena (also knon as Kumara, Subrahmanya, Kartikeya and Skanda), the commander of the Army of Devas, who were the enemies of Asuras, and the gods of Ancient Indians.
There took place that encounter, so fearful to both sides: for all the battle-field was covered with blood and strewn with the bodies of both Devas (gods) and Asuras. But the Devas were soon worsted all on a sudden, and the terrible Danavas again made a great havoc of the celestial army. Then the Asuras, drums struck up and their shrill bugles were sounded; and the Danava chiefs yelled their terrific war-cry.
Then a powerful Danava named Mahisha, taking a huge mass of rock in his hands, came out of that terrible Daitya army. He looked like the sun peering forth from against a mass of dark clouds. The celestials, beholding that he was about to hurl that mass of rock at them, fled in confusion. But they were pursued by Mahisha, who hurled that hillock at them. Mahisha struck terror into the hearts of the gods, and with his attendant Danavas he fell upon them like a lion attacking a herd of deer. And when Indra and the other celestials observed that Mahisha was advancing to the charge, they fled, leaving behind their arms and colours. And Mahisha was greatly enraged at this, and he quickly advanced towards the chariot of Rudra; and reaching near, he seized its pole with his hands.
The mighty Mahasena (the leader of the Army of Devas) discharged a bright Sakti (a missile) for the destruction of Mahisha. That missile cut off the head of Mahisha, and he fell upon the ground and died.
Skanda then, in that battle, slew Mahisha who was surrounded by eight padmas (a military unit) of Daityas.
Here, Durga (a goddess) is said to kill Mahisha. This story is elaborated in the Markandeya Purana.
Thou (Druga) shinest also with peacock-plumes standing erect on thy head, and thou hast sanctified the celestial regions by adopting the vow of perpetual maiden-hood. It is for this, O thou that hast slain the Mahishasura (Asura Mahisha).
There are other kingdoms in the south. They are the Dravidas, the Keralas, the Prachyas, the Mushikas, and the Vanavashikas; the Karanatakas, the Mahishakas, the Vikalpas, and also the Mushakas; the Jhillikas, the Kuntalas, the Saunridas, and the Nalakananas; the Kankutakas, the Cholas, and the Malavayakas; the Samangas, the Kanakas, the Kukkuras, and the Angara-marishas; the Samangas, the Karakas, the Kukuras, the Angaras, the Marishas: the Dhwajinis, the Utsavas, the Sanketas, the Trigartas, and the Salwasena; the Vakas, the Kokarakas, the Pashtris, and the Lamavegavasas; the Vindhyachulakas, the Pulindas, and the Valkalas; the Malavas, the Vallavas, the further-Vallavas, the Kulindas, the Kalavas, the Kuntaukas, and the Karatas; the Mrishakas, the Tanavalas, the Saniyas; the Alidas, the Pasivatas, the Tanayas, and the Sulanyas; the Rishikas, the Vidarbhas, the Kakas, the Tanganas, and the further-Tanganas.
How can one go to heaven, having drunk milk in the town called Yugandhara, and resided in the place called Acyutasthala, and bathed in the spot called Bhutilaya? There (Punjab) where the five rivers flow just after issuing from the mountains, there among the Aratta-Vahikas, no respectable person should dwell even for two days. There are two Pishacas named Vahi and Hika in the river Vipasa. The Vahikas are the offspring of those two Pishacas.
The regions are called by the name of Arattas. The people residing there are called the Vahikas. The lowest of brahmanas also are residing there from very remote times. They are without the Veda and without knowledge, without sacrifice and without the power to assist at other’s sacrifices. The Prasthalas, the Madras, the Gandharas, the Arattas, those called Khasas, the Vasatis, the Sindhus and the Sauviras are almost as blamable in their practices
It is in consequence of the absence of Brahmanas from among them that the Sakas, the Yavanas, the Kamvojas and other Kshatriya tribes have become fallen and degraded into the status of Sudras. The Dravidas, the Kalingas, the Pulandas, the Usinaras, the Koli-Sarpas, the Mahishakas and other Kshatriyas, have, in consequence of the absence of Brahmanas from among their midst, become degraded into Sudras.
Having subjugated the son of Ekalavya, Arjuna then proceeded towards the southern ocean. In those regions battle took place between the diadem-decked hero and the Dravidas and Andhras and the fierce Mahishakas and the hillmen of Kolwa. Subjugating those tribes without having to accomplish any fierce feats, Arjuna proceeded to the country of the Surashtras.