Nakula (Sanskrit: नकुल) is a major character in the ancient Indian epic, the Mahabharata. He is the elder twin brother of Sahadeva and the fourth of the five Pandava brothers. He is the son of twin physician gods, Ashvins, and Madri, the second wife of King Pandu of Kuru dynasty. In the epic, Nakula is described as the most handsome man of his lineage, and was renowned for his skill in swordsmanship and horse keeping.

He was married to Draupadi, as were his four brothers. He was also married to Karenumati of Chedi Kingdom. He had two sons Shatanika and Niramitra from his two wives respectively. During the Rajasuya of his eldest brother Yudhishthira, he conquered the kings of the Sivis, the Rohitakas and other dynasties. After Yudhishthira lost all his possessions to his cousin Duryodhana in a dice game, the Pandavas and Draupadi were exiled for thirteen years. During the Pandavas' year of incognito exile, he disguised as a horse trainer named Granthika, and worked in the kingdom of Virata. Nakula was a skilled warrior who fought in the Kurukshetra War between the Pandavas and their cousins Kauravas. At the end of the epic, during the Pandavas' journey to the Himalayas to enter heaven, Nakula was the third to fall, following Draupadi and Sahadeva, due to his excessive pride in his beauty.

In Sanskrit, the word nakula means "mongoose" or "mongoose-colored."

Nakula and his brother Sahadeva are both also referred to in the epic as Āśvineya, Aśvinīsuta and Aśvisuta because they are the sons of the Ashvins and as Mādravatīputra, Mādravatīsuta, Mādreya, Mādrinandana, Mādrinandanaka, Mādrīputra, Mādrīsuta, Mādrītanūja because they are the sons of Mādrī.

Due to Pandu's inability to bear children (because of the curse of Rishi Kindama), Kunti had to use the boon given by Sage Durvasa to give birth to her three children. She shared the boon with Pandu's second wife, Madri, who invoked the Ashvini Kumaras to beget Nakula and Sahadeva, as twins. Madri committed self immolation, called Sati when her husband died and entrusted her children's care to Kunti. Despite different divine paternal parentage these five children, first three of Kunti – Yudhisthira, Bhima and Arjuna- and latter two of Madri – Nakula and Sahadeva, were called Pandavas, or sons of Pandu. Nakula was known to be the most handsome person in the Kuru lineage.

In his childhood, Nakula mastered his skills in fencing and knife throwing under his father Pandu and a hermit named Suka at the Satasringa ashram. Later, Pandu lost his life when he attempted to make love with his wife, Madri. She committed suicide. Thus, Nakula along with his brothers moved to Hastinapura where he was brought up by Kunti. Kunti loved him as much as her own sons.

Nakula greatly improved his archery and swordplay skills under the tutelage of Drona. Nakula turned out to be an accomplished wielder of the sword. Along with the other Pandava brothers, Nakula was trained in religion, science, administration, and military arts by the Kuru preceptors Kripacharya and Dronacharya. He was particularly skilled at horse-riding.

When the Pandavas and their mother, Kunti were in hiding after the event of Lakshagriha, Arjuna won Draupadi's hand in marriage. Nakula married her along with his brothers and had a son, Shatanika who was killed by Ashwatthama in the Kurukshetra War.