Nathaniel Fiennes, the son of William Fiennes, was born in about 1608. In 1640 he was elected to the House of Commons. A close friend of Oliver Cromwell, he supported the Independents against the Presbyterians.
In 1654 Fiennes was appointed to the Council of State. He also sat in Cromwell's House of Lords. Nathaniel Fiennes died in 1669.