Henotheism (Greek εἷς θεός heis theos "one god") is the belief and worship of a single god while accepting the existence or possible existence of other deities that may also be worshipped. The term was originally coined by Friedrich Wilhelm Joseph von Schelling (1775–1854) to depict early stages of monotheism, however Max Müller (1823–1900), a German philologist and orientalist, brought the term into common usage. Müller made the term central to his criticism of Western theological and religious exceptionalism (relative to Eastern religions), focusing on a cultural dogma which held "monotheism" to be both fundamentally well-defined and inherently superior to differing conceptions of God.

Variations on the term have been "inclusive monotheism" and "monarchical polytheism", designed to differentiate differing forms of the phenomenon. Related terms are monolatrism and kathenotheism, which are typically understood as sub-types of henotheism. The latter term is an extension of "henotheism", from καθ' ἕνα θεόν (kath' hena theon) —"one god at a time". Henotheism is similar but less exclusive than monolatry because a monolator worships only one god (denying that other gods are worthy of worship), while the henotheist may worship any within the pantheon, depending on circumstances, although they usually will worship only one throughout their life (barring some sort of conversion). In some belief systems, the choice of the supreme deity within a henotheistic framework may be determined by cultural, geographical, historical or political reasons.