John Forster (1668 – 2 July 1720) was an Irish lawyer, politician and judge.
His father sat in the Irish House of Commons for Swords and came from a family long associated with the Dublin business community.
Elrington Ball described Forster as "a sound lawyer and impressive speaker" but lacking in political judgment.
His tenure as Recorder of Dublin saw a major conflict between the aldermen of Dublin and the Privy Council; Forster was entirely on the side of the aldermen, and for this, he was violently attacked by Jonathan Swift and other critics.
Forster married firstly Rebecca Monck, daughter of Henry Monck of St. Stephens Green, Dublin and his wife Sarah, daughter and heiress of Sir Thomas Stanley of Grangegorman, by whom he had at least three children, Richard, Anne and Elizabeth.