Pierre Fatio (7 November 1662 - 6 September 1707) was a Swiss politician.
Registered at the University of Basel in 1679 and then in 1685 where he earned a doctorate in law in 1686 , Fatio also studied in Valence, Montpellier and Leiden. Back in Geneva, he made a reputation as a lawyer and followed the usual path of young patricians seeking access to high offices of the Republic.
Elected to the Council of Two Hundred in 1688, he held several positions in Government: lord of Saint-Victor and Chapter in 1691 , auditor in 1696 and lord of Peney in 1700. In 1705 his application for the Little Council was rejected in favor of his brother, Jacques-Francois, who did not have his experience in public affairs.
Fatio was then the spokesman and defender of the bourgeoisie in the struggle against the patricians who now considered him a renegade. During the troubles of 1707, he proposed several reforms, notably the annual meeting of a General Council. However, it this dismissed by the influential fringe of his party who considered his positions too extreme. Claiming his participation in a proposed conspiracy to overthrow the government, the Little Council condemned Fatio to death. He was shot in the courtyard of the prison of the bishopric.