Mercy is a term used to describe the leniency or compassion shown by one person to another, or a request from one person to another to be shown such leniency or compassion. One of the basic virtues of chivalry and Christian ethics, it is also related to concepts of justice and morality in behaviour between people.

Mercy can refer both to compassionate behaviour on the part of those in power (e.g. mercy shown by a judge toward a convict) or on the part of a humanitarian third party (e.g. a mission of mercy aiming to treat war victims).

In a legal sense, such as a defendant having been found guilt of a capital crime, they may ask for clemency from being executed.

The reverse situation applies in the case of euthanasia (mercy killing).

A famous literary example is from The Merchant of Venice when Portia asks Shylock to show mercy. The quality of mercy is not strained, she tells him.

There are also a number of organisations taking 'mercy' into their name to describe their work, including the Mercy Corps, the Sisters of Mercy and the Temple of Mercy and Charity.