Anglo-Saxon paganism, sometimes termed Anglo-Saxon heathenism, Anglo-Saxon pre-Christian religion, Anglo-Saxon traditional religion, or Anglo-Saxon polytheism refers to the religious beliefs and practices followed by the Anglo-Saxons between the 5th and 8th centuries AD, during the initial period of Early Medieval England. A variant of Germanic paganism found across much of north-western Europe, it encompassed a heterogeneous variety of beliefs and cultic practices, with much regional variation.

Developing from the earlier Iron Age religion of continental northern Europe, it was introduced to Britain following the Anglo-Saxon migration in the mid 5th century, and remained the dominant belief system in England until the Christianisation of its kingdoms between the 7th and 8th centuries, with some aspects gradually blending into folklore. The pejorative terms paganism and heathenism were first applied to this religion by Christianised Anglo-Saxons, and it does not appear that the followers of the indigenous faith had a name for their religion themselves; there has therefore been debate among contemporary scholars as to the appropriateness of continuing to describe these belief systems using this Christian terminology. Contemporary knowledge of Anglo-Saxon paganism derives largely from three sources: textual evidence produced by Christian Anglo-Saxons like Bede and Aldhelm, place-name evidence, and archaeological evidence of cultic practices. Further suggestions regarding the nature of Anglo-Saxon paganism have been developed through comparisons with the better-attested pre-Christian belief systems of neighbouring peoples such as the Norse.

Anglo-Saxon paganism was a polytheistic belief system, focused around a belief in deities known as the ése (singular ós). The most prominent of these deities was probably Woden; other prominent gods included Thunor and Tiw. There was also a belief in a variety of other supernatural entities which inhabited the landscape, including elves, nicors, and dragons. Cultic practice largely revolved around demonstrations of devotion, including sacrifice of inanimate objects and animals to these deities, particularly at certain religious festivals during the year. There is some evidence for the existence of timber temples, although other cultic spaces might have been open-air, and would have included cultic trees and megaliths. Little is known about pagan conceptions of an afterlife, although such beliefs likely influenced funerary practices, in which the dead were either interred or cremated, typically with a selection of grave goods. The belief system also likely included ideas about magic and witchcraft,^{[citation needed]} and elements that could be classified as a form of shamanism.^{[citation needed]}

The deities of this religion provided the basis for the names of the days of the week in the English language. What is known about the religion and its accompanying mythology have since influenced both literature and modern paganism.

The word pagan is a Latin pejorative term that was used by Gentile Christianity (also: Pagan Christianity) in Anglo-Saxon England to designate non-Christians. In Old English, the vernacular language of Anglo-Saxon England, the equivalent term was hæðen ("heathen"), a word that was cognate to the Old Norse heiðinn, both of which may derive from a Gothic word, haiþno. Both pagan and heathen were terms that carried pejorative overtones, with hæðen also being used in Late Anglo-Saxon texts to refer to criminals and others deemed to have not behaved according to Christian teachings. The term "paganism" was one used by Gentile Christians as a form of othering, and as the archaeologist Neil Price put it, in the Anglo-Saxon context, "paganism" is "largely an empty concept defined by what it is not (Christianity)".

There is no evidence that anyone living in Anglo-Saxon England ever described themselves as a "pagan" or understood there to be a singular religion, "paganism", that stood as a monolithic alternative to Christianity. These pagan belief systems would have been inseparable from other aspects of daily life. According to the archaeologists Martin Carver, Alex Sanmark, and Sarah Semple, Anglo-Saxon paganism was "not a religion with supraregional rules and institutions but a loose term for a variety of local intellectual world views." Carver stressed that, in Anglo-Saxon England, neither paganism nor Christianity represented "homogenous intellectual positions or canons and practice"; instead, there was "considerable interdigitation" between the two. As a phenomenon, this belief system lacked any apparent rules or consistency, and exhibited both regional and chronological variation. The archaeologist Aleks Pluskowski suggested that it is possible to talk of "multiple Anglo-Saxon 'paganisms'".

Adopting the terminology of the sociologist of religion Max Weber, the historian Marilyn Dunn described Anglo-Saxon paganism as a "world accepting" religion, one which was "concerned with the here and now" and in particular with issues surrounding the safety of the family, prosperity, and the avoidance of drought or famine. Also adopting the categories of Gustav Mensching, she described Anglo-Saxon paganism as a "folk religion", in that its adherents concentrated on survival and prosperity in this world.

Using the expressions "paganism" or "heathenism" when discussing pre-Christian belief systems in Anglo-Saxon England is problematic. Historically, many early scholars of the Anglo-Saxon period used these terms to describe the religious beliefs in England before its conversion to Christianity in the 7th century. Several later scholars criticised this approach; as the historian Ian N. Wood stated, using the term "pagan" when discussing the Anglo-Saxons forces the scholar to adopt "the cultural constructs and value judgements of the early medieval [Christian] missionaries" and thus obscures scholarly understandings of the so-called pagans' own perspectives. At present, while some Anglo-Saxonists have ceased using the terms "paganism" or "pagan" when discussing the early Anglo-Saxon period, others have continued to do so, viewing these terms as a useful means of designating something that is not Christian yet which is still identifiably religious. The historian John Hines proposed "traditional religion" as a better alternative, although Carver cautioned against this, noting that Britain in the 5th to the 8th century was replete with new ideas and thus belief systems of that period were not particularly "traditional". The term "pre-Christian" religion has also been used; this avoids the judgemental connotations of "paganism" and "heathenism" but is not always chronologically accurate.