Sir Arthur Wing Pinero (24 May 1855 – 23 November 1934) was an English playwright and, early in his career, actor.

Pinero was drawn to the theatre from an early age, and became a professional actor at the age of 19. He gained experience as a supporting actor in British provincial theatres, and from 1876 to 1881 was a member of Henry Irving's company, based at the Lyceum Theatre, London.

Pinero wrote his first play in 1877. Seven years later, having written 15 more, three of them highly successful, he abandoned acting and became a full-time playwright. He first became known for a series of farces, of which The Magistrate (1885) was the longest-running. During the 1890s he turned to serious subjects. The Second Mrs Tanqueray (1893), dealing with a woman with a scandalous past, was regarded as shocking, but ran well and made a large profit. His other successes included Trelawny of the "Wells" (1898), a romantic comedy celebrating the theatre, old and new, and The Gay Lord Quex, about a reformed roué and a feisty young woman. A venture into opera, with a libretto for The Beauty Stone (1898), was not a success, and Pinero thereafter generally stuck to his familiar genre of society dramas and comedies.

Although he continued to write throughout the first three decades of the 20th century and into the fourth, it is Pinero's work from the 1880s and 1890s that has endured. There have been numerous revivals of many of his plays; and some have been adapted for the cinema or as musicals. By his later years, Pinero was seen as old-fashioned, and his last plays were not successful. He died in London at the age of 79.