Judge Gwilym Williams was born in Aberdare, to the son of a colliery proprietor.He was educated at Cowbridge grammar school, the Normal College, Swansea, and in France. He became a barrister of the Inner Temple, 1863, and in the same year, on the death of his father, a wealthy landowner, as the proprietor of the Miskin estate.
Gwilym Williams’ family could trace its ancestry back to the last Welsh rulers of Glamorgan, Iestyn ap Gwrgan.
He was a leading judge on the Glamorgan circuit, becoming a well known and powerful figure in Victorian Wales.
Five years after his death his remains were taken from Llantrisant parish church to be re-interred at St David’s Church, Miskin.