Devadatta (Sanskrit and Pali: देवदत्त devadatta; Sinhalese: දේවදත්ත) was by tradition a Buddhist monk, cousin and brother-in-law of Gautama Siddārtha, the Śākyamuni Buddha, and brother of Ānanda, a principal student of the Buddha. Devadatta was a Koliyan and is said to have parted from the Buddha's following with 500 other monks to form their own Sangha, most of whom are said to have been Shakya clan relatives of both Devadatta and Siddhartha.

The name Devadatta has the meaning god-given in Palī and Sanskrit. It is composed from the genitive of deva and the past participle datta of the verb da, give. In the Bhagavad Gītā, the conch shell used by Arjuna on the battle-field of Kurukshetra was named Devadatta. The name Devadatta is still given today, and is often spelled Deodatta.

According to Andrew Skilton, modern scholarship generally agrees that the Mahāsāṃghika Vinaya is the oldest extant Buddhist Vinaya. The Mahāsāṃghika Vinaya is significant for its differing accounts from those of other schools. The Mahāsāṃghika Vinaya mentions the figure of Devadatta, but the description and attributes of this figure are entirely different from those in the vinayas of sects from the Sthavira branch. In fact, there is no overlap in the characterizations of Devadatta between the Mahāsāṃghika Vinaya and the other five extant vinayas which all come from the Sthavira branch. This has led some scholars to conclude that the story of Devadatta was a legend produced by the Sthaviras after they split from the Mahāsāṃghikas in the 4th century BCE.André Bareau has discovered that the earliest vinaya material common to all sects simply depicts Devadatta as a Buddhist saint who wishes for the monks to live a rigorous lifestyle.

Gautama Buddha or Siddhārtha Gautama Buddha (Sanskrit: सिद्धार्थ गौतम बुद्ध; Pali: Siddhattha Gotama) was a spiritual teacher from the Indian subcontinent, on whose teachings Buddhism was founded. The word Buddha is a title for the first awakened being in an era. In most Buddhist traditions, Siddhartha Gautama is regarded as the Supreme Buddha (P. sammāsambuddha, S. samyaksaṃbuddha) of our age, "Buddha" meaning "awakened one" or "the enlightened one." Gautama Buddha may also be referred to as Śākyamuni (Sanskrit: शाक्यमुनि "Sage of the Śākyas"). The Buddha found a Middle Way that ameliorated the extreme asceticism found in the Sramana religions.

The time of Gautama's birth and death are uncertain: most early 20th-century historians dated his lifetime as c. 563 BCE to 483 BCE, but more recent opinion dates his death to between 486 and 483 BCE or, according to some, between 411 and 400 BCE. UNESCO lists Lumbini, Nepal, as a world heritage site and birthplace of Gautama Buddha. There are also claims about birth place of Gautama Buddha to be Kapileswara, Orissa or Kapilavastu at Piprahwa, Uttar Pradesh He later taught throughout regions of eastern India such as Magadha and Kośala.