The Reverend David Rees (14 November 1801– 31 March 1869) was a Welsh Congregational minister of Capel Als chapel Llanelli, Carmarthenshire, and an editor of a radical Welsh language Nonconformist periodical titled Y Diwygiwr (The Reformer). He was best known as ‘Y Cynhyrfwr’ ('The Agitator'), his radical political views, and his opposition to the relationship between the Established Church and the state.
Rees, son of Bernard and Anna Rees, was born and raised on the Gelli Lwyd farm in the parish of Trelech, Carmarthenshire. Whilst a child he worked on his family’s farm as well as spending some time with the local blacksmith, as an apprentice.
Rees did not have any formal education as a child but was instructed at the Sunday school and participated in Christian worship regularly at home with his family.
In 1818 he became a member of Tre-lech Congregationalist church under the ministry of the Calvinistic minister Morgan Jones, and in 1822 with the aim of becoming a preacher, he enlisted as a student in a school in Haverfordwest, Pembrokeshire and later studied for a time at Carmarthen Grammar School.
Rees started preaching in 1823 at the age of 22 and after spending some time at a school in Newtown, Montgomeryshire, in 1825 he joined the Congregationalist academy, also in Newtown. Rees studied at the academy for four years and became familiar with some of the most notable Welsh Congregationalists of his time. One of these was the young Samuel Roberts, Llanbrynmair (S.R.) who was later to become a Congregational minister and editor of another radical Welsh publication Cronicl y Cymdeithasau Crefyddol ("Chronicle of Religious Societies").