Francis Fergus O’Farrell was an Irish soldier of the seventeenth century. O’Farrell was originally from County Longford, but settled in the Dutch Republic where he married and had children. O'Farrell joined the Dutch Army of William III. O’Farrell was commissioned into the English Army as a Colonel following the Glorious Revolution of 1688. He served in Ireland under William during the War of the Two Kings which led to the defeat of the Jacobites under James II.