John Wesley (pronounced /ˈwɛslɪ/) (28 June 1703 – 2 March 1791) was an Anglican cleric and Christian theologian. Wesley is largely credited, along with his brother Charles Wesley, with founding the Methodist movement which began when he took to open-air preaching in a similar manner to George Whitefield. In contrast to George Whitefield's Calvinism (which later led to the forming of the Calvinistic Methodists), Wesley embraced Arminianism. Methodism in both forms was a highly successful evangelical movement in the United Kingdom, which encouraged people to experience Christ personally.

Wesley helped to organise and form societies throughout England, Scotland, Wales and Ireland; small groups that developed intensive, personal accountability, discipleship and religious instruction among members. His great contribution was to appoint itinerant, unordained preachers who travelled widely to evangelise and care for people in the societies. Young men who acted as their assistants were called "exhorters" who functioned in a similar fashion to the twelve apostles after the ascension of Jesus.

Under Wesley's direction, Methodists became leaders in many social justice issues of the day, including the prison reform and abolitionism movements. Wesley's contribution as a theologian was to propose a system of opposing theological stances. His greatest theological achievement was his promotion of what he termed "Christian Perfection", or holiness of heart and life. Wesley held that, in this life, Christians could come to a state in which the love of God, or perfect love, reigned supreme in their hearts. His evangelical theology, especially his understanding of Christian perfection, was firmly grounded in his sacramental theology. He continually insisted on the general use of the means of grace (prayer, scripture, meditation, Holy Communion, etc.) as the means by which God sanctifies and transforms the believer.