Leviticus (Greek: Λευιτικός, "relating to the Levites") or Vayikra (Hebrew: ויקרא, literally "and He called") is the third book of the Hebrew Bible/Christian Old Testament, and the third of five books of the Jewish Torah or Pentateuch.

Leviticus contains laws and priestly rituals, but in a wider sense is about the working out of God's covenant with Israel set out in Genesis and Exodus – what is seen in the Torah as the consequences of entering into a special relationship with God (specifically, Yahweh). These consequences are set out in terms of community relationships and behaviour.

The first 16 chapters and the last chapter make up the Priestly Code, with rules for ritual cleanliness, sin-offerings, and the Day of Atonement, including Chapter 12 which mandates male circumcision. Chapters 17-26 contain the Holiness Code, including the injunction in chapter 19 to "love one's neighbor as oneself" (the Great Commandment). The book is largely concerned with "abominations", largely dietary and sexual restrictions. The rules are generally addressed to the Israelites, except for the prohibition in chapter 20 against sacrificing children to Molech, which applies equally to "the strangers that sojourn in Israel."

According to tradition, Moses authored Leviticus as well as the other four books of the Torah . Modern biblical scholars believe Leviticus to be almost entirely from the priestly source (P), marked by emphasis on priestly concerns, composed c 550-400 BC, and incorporated into the Torah c 400 BC.