Eirwen Meiriona St John Gwynn (née Williams; Welsh: [ˈe(i)ruːɛn] / ˈ aɪər w ɛ n / ; 1 December 1916 – 26 January 2007) was a Welsh nationalist writer, teacher and physicist. Born in Liverpool, she read physics at the University College of North Wales and later earned a Doctor of Philosophy degree in that field in 1942. Gwynn taught physics at Rhyl Grammar School and later worked as an assistant account at the Government Exchequer and Audit Department. She then worked as a full-time lecturer for the Workers' Educational Association and was a freelance writer who created 1,500 works on social development and science in the English and Welsh printed press. Gwynn also authored multiple books and short stories, won awards during her career, promoted the Welsh language by being a member of four committees and served as president of two societies.