A deal with the Devil (also called a pact with the Devil, Faustian bargain, or Mephistophelian bargain) is a cultural motif exemplified by the legend of Faust and the figure of Mephistopheles, as well as being elemental to many Christian traditions. According to traditional Christian belief about witchcraft, the pact is between a person and the Devil or another demon, trading a soul for diabolical favours, which vary by the tale, but tend to include youth, knowledge, wealth, fame and power.

It was also believed that some people made this type of pact just as a sign of recognising the minion as their master, in exchange for nothing. The bargain is a dangerous one, as the price of the Fiend's service is the wagerer's soul. The tale may have a moralising end, with eternal damnation for the foolhardy venturer. Conversely, it may have a comic twist, in which a wily peasant outwits the devil, characteristically on a technical point. The person making the pact sometimes tries to outwit the devil, but loses in the end (e.g., man sells his soul for eternal life because he will never die to pay his end of the bargain. Immune to the death penalty, he commits murder, but is sentenced to life in prison).

A number of famous works refer to pacts with the devil, from the numerous European Devil's Bridges to the violin virtuosity of Giuseppe Tartini and Niccolò Paganini to the "crossroad" myth associated with Robert Johnson.

In Stith Thompson's Motif-Index of Folk-Literature, "Bargain with the devil" constitutes motif number M210 and "Man sells soul to devil" motif number M211.