Robert Williams (25 May 1830 - 5 August 1877), usually referred to by his bardic name Trebor Mai, was a Welsh language poet, born at Ty'n-yr-ardd near Llanrhychwyn, near Llanrwst, in the old county of Caernarfonshire, the son of a tailor.
Around 1843, he moved with his family to Llanrwst and he applied himself to his father's craft.
After he married on 13 October 1854 he commenced business as a tailor himself in Llanrwst, and remained there for the rest of his life.
He published two small volumes in his lifetime, Fy Noswyl (1861) and Y Geninen (1869).
The contents of these with large additions were published posthumously as Gwaith Barddonol Trebor Mai (Isaac Ffoulkes, Liverpool, 1883).