| Honorific-Prefix: | Mayor |
| Francis Cassidy | |
| Order: | 14th Mayor of Montreal |
| Term Start: | February 1873 |
| Term End: | June 1873 |
| Predecessor: | Charles-Joseph Coursol |
| Successor: | Aldis Bernard |
| Office2: | Member of the Legislative Assembly of Quebec for Montréal-Ouest |
| Term Start2: | 1871 |
| Term End2: | 1873 |
| Successor2: | John Wait McGauvran |
| Birth Date: | 17 January 1827 |
| Birth Place: | Saint-Jacques-de-l’Achigan, Lower Canada |
| Death Place: | Montreal, Quebec |
| Resting Place: | Notre Dame des Neiges Cemetery |
| Profession: | lawyer |
Francis Cassidy, (17 January 1827 – 14 June 1873) was a Canadian lawyer and politician, the Mayor of Montreal, Quebec for three months in 1873, until his term was cut short by death.
Cassidy was born at Saint-Jacques-de-l’Achigan, in what is today Quebec's Montcalm Regional County Municipality, Quebec. Despite spending childhood in a poor family, he attended Collège de l’Assomption with the support of Abbé Étienne Normandin. He began legal studies in Montreal, formally becoming a lawyer on 18 August 1848. After developing a distinguished legal career, he was designated Queen's Counsel on 5 August 1863.
He was a founder of the Institut canadien de Montréal and served as its president between 1849 and 1850 and again between 1857 and 1858. From 1871 to 1873, he served as a Conservative member for Montréal-Ouest riding during the first portion of the 2nd Legislative Assembly of Quebec.
Just months after becoming Montreal's uncontested mayor in February 1873, Cassidy died in office that June. He was entombed at the Notre Dame des Neiges Cemetery in Montreal.[1] He never married.