Nonconformist was a term used in England after the Act of Uniformity 1662 to refer to an English subject who separated himself from the established state Church of England. It may also refer more narrowly to such a person who also advocated religious liberty.

The term was applied to early English Protestants (such as Puritans and Presbyterians) who violated the Act of Uniformity 1559, typically by practicing or advocating radical, sometimes separatist, dissent with respect to the established state church.

Presbyterians, Congregationalists, Baptists, and those less organized, were considered Nonconformists at the time of the 1662 Act of Uniformity.

The term "dissenter" came into use particularly after the Act of Toleration (1689), which exempted nonconformists who had taken the oaths of allegiance from penalties for nonattendance at the services of the Church of England.