Slava (Serbian: Слава, lit. 'Celebration', pronounced [ˈslâʋa]) is a family's annual ceremony and veneration of their patron saint. The ceremony is found mainly among Orthodox Serbs.

Although its origin is unknown, this old tradition is an important ethnic marker of Serbian identity. It is a tribute to the family's first ancestor, who was baptized into Christianity, with its presiding saint. Slava is passed down exclusively through male lineage and it symbolizes family identity, unity, and faith.

In 2014, Slava was inscribed on UNESCO Intangible Cultural Heritage Lists of Serbia. In general, the observance of Slava remains one of the most enduring and cherished traditions among Serbs worldwide.

Serbian historians consider that records of Slava amongst Serbs can be traced back at least to 1018. However, the true origin of the Slava is unknown. According to one hypothesis, the Slava has its origins in Greek and Roman hero cult. Proponents of the Greek hypothesis point to etymology in that the Serbian word for wheat, koljivo, an indispensable item of the Slava, is derived from the Greek term for gain of wheat, koliva. Proponents of the Roman hypothesis point to the fact that Slava customs mimic Roman forms of celebration including bread breaking and toasting. Another hypothesis states that the Slava has its origin in Medieval Serbia, connected to Saint Sava, the first Archbishop of the Serbs. There are indications that the institution of the Slava in the Serbian Orthodox Church dates from Saint Sava, that "in his understanding and tactful approach to Serbian folk religion", he "seems to have found a compromise formula satisfactory to both his people's pagan tradition and the requirements of theology". The slava is a reinterpretation of a Serbian pagan rite: the ancestor-protector became a Christian saint, frequently St. Nicholas, with the pagan rite being reduced of many religious elements and frequent ceremonies and becoming a social event with the annual meeting of the family and friends.

In the scientific literature exists a discussion about the historical and ethnological origin of the Slava, which has not been completed. According to some Serbian researchers, "the thesis of how Slava is Serbian ethnic identification marker is simply delusion of the romantic and patriotic citizenry".

The increased effective geographic mobility brought about by the post World War II urbanization of a previously highly agrarian society, combined with the suppression of Serbian Orthodox traditions under the Communist rule, has made some aspects of the custom more relaxed. In particular, in the second half of the 20th century it became common to see traditional patriarchal families separated by great distances, so by necessity Slava came to occasionally be celebrated at more than one place by members of the same family.

While the Slava kept something of a grassroots underground popularity during the Communist period, the post-Communist revival of Serbian Orthodox traditions has brought it a resurgence. It is recognized as a distinctly (if not quite exclusively) Serbian custom, and today it is quite common for nonobservant Christians or even atheists to celebrate it in one form or another, as a hereditary family holiday and a mark of ethnocultural identification.

The custom is also helpful in genealogical studies as an indicator in kinship relations between families, such as tracing one's family to a specific region. It "becomes a simultaneous signifier of national and spiritual kinship and a core expression of the Serbian cosmology, whereby the dialectics of temporal, physical, and spiritual continuity converge into validated perceptions of cultural and social reality—re-enacted on a recurrent (annual) basis.