Sahadeva (Sanskrit: सहदेव, romanized: Sahadeva, lit. 'one with the gods') was the youngest of the five Pandava brothers in the ancient Indian epic, the Mahabharata. He and his twin brother Nakula were the sons of Madri, one of the wives of the Pandava patriarch Pandu, and Ashvini Kumaras, the divine twin physicians of the gods, whom she invoked to beget her sons due to Pandu's inability to progenate. Sahadeva is renowned for his wisdom, knowledge of astrology, and skill in swordsmanship.

Sahadeva was married to Draupadi, as were his four brothers. He was also married to Vijaya of Madra kingdom. He had two sons, Shrutasena and Suhotra, from his two wives respectively. Sahadeva played a crucial role during the Rajasuya of Yudhishthira, where he conquered the kings of the South. After Yudhishthira lost all of his possessions to Duryodhana in the game of dice, Sahadeva vowed to slay Shakuni, Duryodhana's maternal uncle, who had used loaded dice to unfairly win the game. Afterwards, the Pandavas and Draupadi were exiled for thirteen years, with the last year being a period of hiding called as Agyaata Vaasa. During the hiding, Sahadeva disguised himself as a Vaishya named Tantripala and worked as a cowherd in the kingdom of Virata. Sahadeva was a skilled warrior who fought in the Kurukshetra War between the Pandavas and their cousins, the Kauravas. On the 18th day of the war, he slayed Shakuni. At the end of the epic, during the Pandavas' journey in the Himalayas to enter Svarga, Sahadeva was the second to fall, following Draupadi, due to his excessive pride in his wisdom.

The word sahadeva is derived from two Sanskrit words saha (सह) and deva (देव). Saha means ‘with’ and deva is a Hindu term used for ‘deity’. So literally, Sahadeva means ‘with the gods’ or ‘protected by the gods’. In southern India, he is regarded as a very accomplished astrologer, a face reader, and a master of all other forms of intuitive perception. He was known for his secretive nature; although he accurately understood a situation, he never revealed anything about it. Hence, presently, people who have a similar nature are called a Sahadeva.

In the epic, various epithets for Sahadeva has been used. Prominent ones are the patronymics—Āśvineya, Aśvinīsuta—and matronymics—Mādrīputra, Mādreya. Other important other names are Bharataśārdūla, Bharatasattama, Kauravya, Kurunandana, Nakulānuja, Pāṇḍava and Pāṇḍunandana.

The story of Sahadeva is told in the Mahabharata, one of the Sanskrit epics from the Indian subcontinent. Sahadeva also appears in later Hindu scriptures like the Harivamsa—which is regarded as khila (supplement or appendix) of the Mahabharata—and Puranas like the Bhagavata Purana.

Sahadeva was one of the five brothers born to Pandu, a member of the illustrious Lunar dynasty lineage and the heir of the throne of Kuru. The collective name “Pandavas” originates from their father. However, Pandu was afflicted by a curse that would lead to his demise if he engaged in sexual relations with a woman. Consequently, Sahadeva and his brothers were born through a sacred mantra bestowed upon Pandu's first wife Kunti by the revered sage Durvasa during her maidenhood. Both of Pandu’s wives—Madri and Kunti—invoked different deities and were blessed with children.

According to the Adi Parva ('First Book') of the Mahabharata, upon Pandu's behest, Kunti had used her boon three times to invoke celestial gods and gave birth to her three children—Yudhishthira, Bhima and Arjuna. Upon hearing about Madri's desire to give birth to a son, Pandu requested Kunti to share her boon with her. Madri, upon seeking divine assistance, invoked the twin celestial deities of health, the Asvins, and bore two sons—Nakula and Sahadeva—who were extolled to be unparalleled in earthly beauty. An ethereal voice proclaimed that these twins would surpass even the Asvins themselves in energy and allure. Despite invoking the gods only once, Madri obtained two remarkable sons. However, her co-wife, Kunti, fearing that Madri might surpass her in offspring, beseeched the king not to command her further, accepting this as her granted boon. Sahadeva, along with his brothers, spent his childhood in the company of sages at Shatashriga mountain. However he was orphaned after Pandu, who had a curse inflicted upon him by Kindama, attempted to engage in love making with Madri, resulting in his demise. Following this, Madri entrusted her children to Kunti, and followed him to his death by performing the ancient practice of sati, immolating herself on her husband’s funeral pyre. Kunti raised the twins alongside her own sons in Hastinapura, the capital of Kuru which was being ruled under Pandu's elder brother Dhritarashtra. Despite Sahadeva not being her biological offspring, Kunti held a special affection for him, making him her favorite among the Pandavas. The Pandava brothers were brought up with their paternal cousins, the Kauravas, and the education of all these boys was supervised by Bhishma.

Sahadeva and Nakula, along with the other princes, were instructed in the gurukula for by Kripa and Drona in warfare and use of weapons such as bow and arrows and martial art. He also mastered his skills in fencing and axe fighting. After completing their training, the Pandavas defeated Drupada, King of Panchala, as a gurudakshina for Drona. Notably, Sahadeva along with Nakula protected the wheels of Arjuna's chariot during this endeavor. Later, Duryodhana—the eldest son of Dhritarashtra and leader of hundred Kaurava brothers—plotted to burn the Pandavas alive by constructing Lakshagriha, a lac palace, in Varanavata. Fortunately, with the aid of their wise uncle Vidura, the Pandavas escaped through a secret tunnel.