The epitome of sins.
The fifteenth son born to Brahma’s son Kashyapa and his wife Muni. He was a devagandharva. His brothers were Ugrasena, Bhimasena, Suparna, Varuna, Gopati, Dhritarashtra, Suvarchas, Satyavak, Arkaparna, Prayuta, Vishruta, Chitraratha, Shalishiras, Parjanya, Narada as per Mahabharata Adiparva Chapter 65 verse 43.
After Krishna attained Vaikuntha, the Pandavas entrusted the kingdom to Abhimanyu’s son Parikshit and started on their mahaprasthana. While Parikshit was completing his digvijaya, Kali appeared before him in the form of a shudra king, hurting a cow. Parikshit raised his bow to kill him, but refrained when Kali bowed before him. Parikshit asked him to go away from his kingdom, but Kali said that the whole world belonged to Parikshit, so Parikshit should give him a place to stay. Parikshit gave him five abodes – gambling, alcohol, women, killing and gold. From then on, Kali resides in all these, as per Bhagavata Prathamaskanda Chapter 17.
In Brahma’s lifetime, there are 14 manvantaras. Each manvantara has a different Manu, and 4 yugas of its own – Kritayuga, Tretayuga, Dwaparayuga, Kaliyuga. This is the seventh manvantara. It is believed that Kritayuga lasts for 1728000 years, Tretayuga for 1296000 years, Dwaparayuga for 864000 years and Kaliyuga for 432000 years. This Kaliyuga began in BC 3102 and will last more than 426000 years now, after which the eighth manvantara will begin. Kali (sins) plays the most important role in the last yuga, as per Mahabharata Vanaparva Chapter 88. It is believed that Kali was born on the day that Krishna ascended Vaikuntha, as per Bhagavatamahatmya Chapter 1 verse 66.
When Indra and other devas were returning from Damayanti’s swayamwar, they saw the Kalidwaparas who were planning to attend it. The Kalidwaparas learned that Nala had married Damayanti. Kali was irritated that she had ignored devas and married a mortal. He decided to take away Nala’s kingdom and disrupt their married life. Dwapara agreed to support him. Kali began following Nala and this continued for 12 years. Once Nala forgot to do his ablutions before his evening prayer. Kali chose that opportunity to enter him. Kali then took the form of a bull and approached Nala’s brother Pushkara. Nala challenged Pushkara to a gambling game for the bull. Pushkara agreed. The game continued and Nala lost his kingdom too. He went away to the forest with Damayanti, but left her alone there soon after. Damayanti cursed Kali. Nala meanwhile rescued Karkodaka from a forest fire. When Nala was roaming in the forest, separated from Damayanti, Karkodaka bit him and transformed his appearance, and said that Kali who ahd cheated Nala would stay as the venom in him. He gave him a shawl to revert to his original self whenever he desired. As per Karkodaka’s advice, Nala went as Bahuka to the court of Rituparna, the king of Ayodhya, and stayed there as his charioteer.
Damayanti got to know that Nala was in Rituparna’s court via the messenger Parnada. To lure him out, Damayanti sent a message to Rituparna via a brahmin called Sudeva asking him to attend her marriage the next day. Rituparna asked Bahuka to get him there fast. On the way, Rituparna’s cloak accidentally fell off. Rituparna asked Nala to stop the chariot, but Nala informed him that the chariot had already crossed a yojana in a second. On seeing a huge tree in the forest, the king informed Nala that that it had 5 crore leaves and 2095 fruits. Nala was amazed. They both confided – Nala was able to drive the chariot with such speed because of the Ashwahridaya mantra, and the king was able to know the number of leaves and fruits because of the Akshahridaya mantra. They taught each other the mantras.
As soon as Nala learned the mantra, he vomited the venom, and Kali left him. Nala was about to curse Kali, but refrained when Kali pleaded with him. Kali climbed a big tree and stayed there till Nala went away, as per Mahabharata Vanaparva Chapter 58.
As per Mahabharata Vanaparva Chapter 188, the sage Markandeya predicted that in the Kaliyuga, everyone would be untruthful. Yajnas and charity would barely exist. Brahmins would do the work that shudras did, and the shudras would become wealthy. The lifespans would decrease, and bodies would become smaller. The number of people who could be compared to animals would increase. Nothing would appease the sense organs. Brahmins would sell the vedas, people would even sell rice, and women would sell themselves. tress would bear lesser fruits and flowers, cows would give lesser milk and the number of crows would increase. Brahmins would beg and sages would become merchants. People would ignore the four ashramas. Pupils would disrespect their gurus. There would be regular droughts and famines. There would be genocides, and people would become corrupt. Girls of less than 10 years would give birth and young lads would become fathers. People will start aging at 16 years, and old men will behave like young men. Entire populations will die in famines.
Mahabharata Vanaparva Chapter 85 mentions that the Ganga is the most important holy place in the Kaliyuga.
Duryodhana was an incarnation of Kali and Dwapara was born as Shakuni as per Ashramaparva Chapter 31.