James Richard Atkin, Baron Atkin, PC, FBA (28 November 1867 – 25 June 1944), known from 1913 to 1919 as Sir Richard Atkin and also called Dick Atkin, was an Australian-British barrister who served as a judge of the King's Bench division of the High Court of Justice, a justice of the Court of Appeal, and finally as a lord of appeal in ordinary from 1928 until his death in 1944. He is especially remembered as the judge who gave the leading judgement in the 1932 case Donoghue v Stevenson, which established the modern law of negligence in the UK and indirectly in most of the common law world.

Atkin was the son of Robert Travers Atkin (1841–1872) and his wife, Mary Elizabeth née Ruck (1842–1920). Robert was from Kilgarriff, County Cork, Mary's father from Newington, Kent, and her mother from Merioneth, Wales. The couple married in 1864 and soon emigrated to Australia intending to take up sheep farming. However, little more than a year into their enterprise Robert was badly injured in a fall from a horse and the couple moved to Brisbane where Robert became a journalist and politician.

Atkin was born at Ellandale cottage, Tank Street, off North Quay, Brisbane, the eldest of three sons. In 1871, his mother brought him and his brothers back to her own mother's house, "Pantlludw" on the River Dovey in Wales. His father died in Brisbane in the following year. Atkin was much influenced by his grandmother and acquired from her an egalitarian instinct and a distaste for sanctimonious posturing. His mother's sister, Amy, was the first wife of Francis Darwin, third son of Charles Darwin (1809–1882) and his wife Emma: there is a thank-you letter extant to Charles Darwin from the eleven-year-old Atkin.

Atkin attended Friars School, Bangor, and Christ College, Brecon, and won a demyship to Magdalen College, Oxford, where he read classics and literae humaniores, enjoying playing tennis in his leisure time. Atkin always thought of himself as a Welshman, and was President of the London Welsh Trust from 1938 to 1944.

Atkin was called to the bar from Gray's Inn in 1891 and scoured the London law courts assessing the quality of the advocates so as to decide where to apply for pupillage. He was ultimately impressed by Thomas Scrutton and became his pupil, joining fellow pupils Frank MacKinnon, a future Lord Justice of Appeal, and Robert Wright, another future Law Lord. He took chambers at 3 Pump Court but, as did most beginning barristers at the time, struggled to find work. He shared living accommodation with Arthur Hughes, who later married Mary Vivian Hughes whose book A London Family 1870–1900 mentions Atkin. He eventually established a practice in commercial law, in particular in work on behalf of the London Stock Exchange, and became known as a subtle advocate with no need to rely on theatrical effects. His practice grew from about 1900, and he made a favourable impression when appearing before the future prime minister H. H. Asquith who was sitting as an arbitrator. Asquith was so impressed that he secured a pupillage for his own son Raymond at Atkin's chambers. By 1906, The Times considered Atkin probably the busiest junior at the Bar. In that year, Atkin took silk. Once John Hamilton was made a judge in 1909 and Scrutton in 1910, Atkin dominated the commercial Bar.

Atkin was appointed as a judge of the King's Bench Division of the High Court of England and Wales in 1913, receiving a knighthood. Work at the King's Bench involved him in criminal cases, which had been outside his experience as an advocate, but he established a high reputation as a criminal judge. Reputedly, Atkin enjoyed his six years at the King's Bench more than any others of his legal career. The following nine at the Court of Appeal he enjoyed the least.

Atkin became a Lord Justice of Appeal in 1919. In the 1920 case of Meering v Graham-White Aviation Co Ltd Atkin showed his disapproval of unjustified restriction on civil liberties by holding (obiter) that a person could sue for false imprisonment even under circumstances where he had been unaware of his imprisonment at the time. Again in 1920, in Everett v Griffiths, Atkin held that Everett was owed a duty of care by a Board of Guardians who had detained him as insane on inadequate grounds. However, Lord Justices Scrutton and Bankes held otherwise and their majority prevailed over Atkin's dissenting judgment.

From 1928 until his death he was a Lord of Appeal in Ordinary under the title Baron Atkin of Aberdovey, in the County of Merioneth.