What religions in the world require chastity or celibacy by their religious leaders/priests?
Only the Latin Catholic Rite and some Eastern have a full ban on married priests.
Orthodox and manny eastern churches allow it with certain restrictions (like for example not being able to marry after ordination or get advanced clerical positions if married).
In most other religions priests are not fully celibate, maybe temporarily as part of certain purification rituals, though I'm sure there are local instances with celibate practices even in some religions that do not demand it in general.
Other christian denominations and other Abrahamic faiths (Islam, Judaism) in general do not require celibacy.
Sramanas (Buddhists and Jains) do not really have priests, only monks, but in manny places those functions bland. In some Buddhist lineages like most Japan orders, Taego (Japan-influenced) and some other orders in Korea, some new movements etc celibacy of monks (or even the whole Vinaya - monastic lineage and regulation ) is also lost.
(post)Vedic Hindu priests (Brahmins) are not celibate.
Hindu monasticism, generally shaped on the Sramana (mostly Buddhist) example is also celibate.
In general specialized contemplative monastic organisations that tend to separate from the society tend to be celibate while ritual specialists within the society (priests) even if expected to follow a higher standard of ethical and ritual purity tend not to be.
The Eastern Orthodox Church allows marriage before men enter the priesthood, and therefore allows them to have sex within marital confines; but those who do not marry before must remain celibate.
Most Protestant Churches disdain celibacy.
In most types of Buddhism, monks and nuns must remain celibate.
In areas where Buddhism merges with the traditional religion, this carries over; thus there are certain regions of Taoism where the priests must be celibate.
Certain schools of Hinduism require celibacy to advance toward liberation; but depending on the school, this is either a short-term period in life or a permanent decision. Some Brahmans can marry, others can't.
Jainism encourages celibacy of monks, but not of laymen
Islam, the Bahá'í Faith, and modern Judaism all allow their leaders to marry and have sex within marriage.
I am unsure of opinions regarding Zoroastrianism, as well as local religions of Africa, South America, Native Americans, and the Pacific Islands.
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