David Martyn Lloyd-Jones was a Welsh Protestant minister, preacher and medical doctor. For almost 30 years, he was the minister of Westminster Chapel in London.  He was influential in the Reformed wing of the British evangelical movement in the 20th century.

Lloyd-Jones was born in Cardiff and raised in Llangeitho, Ceredigion. His father was a grocer, and he had two brothers: Harold died during the 1918 flu pandemic, while Vincent went on to become a High Court judge.  Lloyd-Jones obtained an MD from London University, and became a Member of the Royal College of Physicians.

After struggling for two years over what he sensed was a calling to preach, in 1927 Lloyd-Jones returned to Wales, having married Bethan Phillips (with whom he later had two children, Elizabeth and Ann), accepting an invitation to minister at a church in Aberavon.

Lloyd-Jones provoked a major dispute in 1966 when, he called on all clergy of evangelical conviction to leave denominations that contained both liberal and evangelical congregations. Lloyd-Jones had hoped to encourage those Christians who held evangelical beliefs to withdraw from any churches where alternative views were present.