Richard Gerald Lyon-Dalberg-Acton, 4th Baron Acton, Baron Acton of Bridgnorth (30 July 1941 – 10 October 2010) was a British Labour Party politician and peer.

The oldest son of John Lyon-Dalberg-Acton and Daphne Strutt, daughter of Robert Strutt, 4th Baron Rayleigh, he was educated at St George's College in Salisbury, Southern Rhodesia (now Harare, Zimbabwe) and at Trinity College, Oxford, from which he emerged with a Bachelor of Arts in 1963 (later, he would receive a Master of Arts from the same institution).

He served a term as director of Coutts & Co before being admitted to Inner Temple in 1976 and practising law for about four years. He then served as a Senior Law Officer of the Ministry of Justice, Legal and Parliamentary Affairs of Zimbabwe from 1981 until 1985.

He became the 4th Baron Acton, as well as 11th Baronet of Aldenham in 1989, upon his father's death. He lost his seat in the House of Lords after the passage of the House of Lords Act 1999, which he notably supported.^[1] However, on 17 April 2000, he was created a life peer as Baron Acton of Bridgnorth, of Aldenham in the County of Shropshire,^[2] enabling him to return to the House.^[3][4]

Lord Acton sat on the Labour benches and served on the Constitution Committee and on the Joint Committee on Consolidation Bills.

From 1965 to 1973, Acton was married to Hilary Cookson, with whom he had a son, Johnny. After having been a widower for a year, he married Judith Todd, the daughter of Sir Garfield Todd, former Prime Minister of Southern Rhodesia. The marriage ended in 1984.

In 1988, Acton married his third wife, Patricia Nassif, a professor at the University of Iowa College of Law in Iowa City, Iowa. He divided his time between London and Cedar Rapids in Iowa. The couple remained married until his death.

Lord Acton was succeeded by his son from his first marriage and only child John Lyon-Dalberg-Acton, 5th Baron Acton.