Fitzwilliam Square is a small but historic Georgian square in the south of central Dublin, Ireland. It was the last of the five Georgian squares in Dublin to be built. The square was developed by Richard FitzWilliam, 7th Viscount FitzWilliam, hence the name. It was designed from 1789 and laid out in 1792. The center of the square was enclosed in 1813 through an Act of parliament. To the north is the much larger Merrion Square, with which Richard FitzWilliam was also involved. The square was a popular place for the Irish Social Season of aristocrats entertaining in Dublin between January and Saint Patrick's Day each year.
Shootings took place in the square during Bloody Sunday of 1920. Sir Thomas O'Shaughnessy (1850–1933), the last Recorder of Dublin, lived in Fitzwilliam Square and died there on 7 March 1933. The N11 road passes through the northwest side of the square on its way into central Dublin.