Peter John Mitchell Thomas, Baron Thomas of Gwydir, PC, (July 31, 1920-) was a Welsh Conservative politician.

Educated at Jesus College, Oxford, he served in the RAF in the Second World War, spending 1941-1945 in a prisoner-of-war camp in Germany. Called to the Bar in 1947 he was elected to Parliament as MP for Conway in 1951. In 1966 he lost his seat, but returned as MP for Hendon South in 1970, a position which he held until retiring in 1987.

During the whole of Edward Heath's premiership he held the position of Secretary of State for Wales.

In 1987 he was awarded a life peerage, the barony of Llanrwst in Gwynedd.