In Sikhism, Buddha is mentioned as the 23rd avatar of Vishnu in the Chaubis Avtar, a composition in Dasam Granth traditionally and historically attributed to Guru Gobind Singh.

Although there are no extant representations of the Buddha in human form until around the 1st century CE (see Buddhist art), descriptions of the physical characteristics of fully enlightened buddhas are attributed to the Buddha in the Digha Nikaya's Lakkhaṇa Sutta (D, I:142). In addition, the Buddha's physical appearance is described by Yasodhara to their son Rahula upon the Buddha's first post-Enlightenment return to his former princely palace in the non-canonical Pali devotional hymn, Narasīha Gāthā ("The Lion of Men").

The times of Gautama's birth and death are uncertain. Most historians in the early 20th century dated his lifetime as circa 563 BCE to 483 BCE. More recently his death is dated later, between 411 and 400 BCE, while at a symposium on this question held in 1988, the majority of those who presented definite opinions gave dates within 20 years either side of 400 BCE for the Buddha's death. These alternative chronologies, however, have not been accepted by all historians.

Scholars are hesitant to make unqualified claims about the historical facts of the Buddha's life. Most accept that he lived, taught, and founded a monastic order during the Mahajanapada era during the reign of Bimbisara (c. 558 – c. 491 BCE, or c. 400 BCE), the ruler of the Magadha empire, and died during the early years of the reign of Ajatasatru, who was the successor of Bimbisara, thus making him a younger contemporary of Mahavira, the Jain tirthankara. Apart from the Vedic Brahmins, the Buddha's lifetime coincided with the flourishing of influential Śramaṇa schools of thought like Ājīvika, Cārvāka, Jainism, and Ajñana. Brahmajala Sutta records sixty-two such schools of thought. It was also the age of influential thinkers like Mahavira (referred to as 'Nigantha Nataputta' in Pali Canon), Pūraṇa Kassapa, Makkhali Gosāla, Ajita Kesakambalī, Pakudha Kaccāyana, and Sañjaya Belaṭṭhaputta, as recorded in Samaññaphala Sutta, whose viewpoints the Buddha most certainly must have been acquainted with. Indeed, Sariputta and Moggallāna, two of the foremost disciples of the Buddha, were formerly the foremost disciples of Sañjaya Belaṭṭhaputta, the skeptic; and the Pali canon frequently depicts Buddha engaging in debate with the adherents of rival schools of thought. There is also philological evidence to suggest that the two masters, Alara Kalama and Uddaka Ramaputta, were indeed historical figures and they most probably taught Buddha two different forms of meditative techniques. Thus, Buddha was just one of the many śramaṇa Philosophers of that time. In an era where holiness of person was judged by their level of asceticism, Buddha was a reformist within the śramaṇa movement, rather than a reactionary against Vedic Brahminism. While the general sequence of "birth, maturity, renunciation, search, awakening and liberation, teaching, death" is widely accepted, there is less consensus on the veracity of many details contained in traditional biographies.

Some Hindus regard Gautama as the 9th avatar of Vishnu. However, Buddha's teachings deny the authority of the Vedas and the concepts of Brahman-Atman. Consequently Buddhism is generally Classified as a nāstika school (heterodox, literally "It is not so") in contrast to the six orthodox schools of Hinduism.

The Buddha is regarded as a prophet by the minority Ahmadiyya sect of Muslims – a sect considered a deviant and rejected as apostate by mainstream Islam. Some early Chinese Taoist-Buddhists thought the Buddha to be a reincarnation of Laozi.

The Christian Saint Josaphat is based on the Buddha. The name comes from the Sanskrit Bodhisattva via Arabic Būdhasaf and Georgian Iodasaph. The only story in which St. Josaphat appears, Barlaam and Josaphat, is based on the life of the Buddha. Josaphat was included in earlier editions of the Roman Martyrology (feast day 27 November) — though not in the Roman Missal — and in the Eastern Orthodox Church liturgical calendar (26 August).