the name rhosddu is formed on the welsh words "rhos", "moor" or "rush pasture", and "ddu", "black". it was formed as a new ecclesiastical parish by an order in council in 1886. the parish contained the townships of acton, bieston and gourton (from the parish of wrexham), the township of borras riffri (from the parish of gresford), and the township of stansty (from the parish of gwersyllt). in 1972, rhosddu reverted to the parish of wrexham.