Peter Wilson Raffan (1863 – 23 June 1940) was a British Liberal politician.
Raffan came from Newbridge, Monmouthshire, and in 1910 was chairman of the Monmouthshire County Council. When a general election was called in January 1910, P W Raffan was selected as Liberal candidate for Leigh in south Lancashire. John Brunner, the sitting Liberal member of parliament, had chosen to stand in Northwich.
The constituency contained a large number of coalminers, and Raffan was opposed not only by the Conservatives, but by Thomas Greenall of the Labour Party, who was a leader of the Lancashire and Cheshire Miners' Federation. Leigh was one of the few seats where Labour and Liberals ran against each other. Raffan won the seat easily. In the Commons Raffan became secretary of the Land Values Group who sought reform in property taxation. He supported women's suffrage, disestablishment of the Church in Wales and the temperance movement.
At the 1918 general election Raffan was re-elected at Leigh as a Liberal and received the "coupon" despite being an opponent of the Coalition Government. At the 1922 election he stood unsuccessfully for election as a Liberal at Ayr Burghs.