| Joseph-Alfred Mongrain | |
| Constituency Mp: | Trois-Rivières |
| Parliament: | Canadian |
| Predecessor: | Léon Balcer |
| Successor: | Claude Lajoie |
| Term Start: | 1965 |
| Term End: | 1970 |
| Birth Date: | 1908 12, mf=y |
| Birth Place: | St-Tite, Mauricie, Quebec |
| Death Place: | Trois-Rivières, Quebec |
| Party: | Liberal Party of Canada |
| Occupation: | Public relations officer |
Joseph-Alfred Mongrain was a politician from Quebec, Canada.
He was born on December 28, 1908, in St-Tite, Mauricie. He was a public relations officer.
He was Mayor of Trois-Rivières from 1949 to 1953 and from 1960 to 1963.
He ran as a Liberal candidate in 1952 in the district of Trois-Rivières against Premier Maurice Duplessis. Duplessis was re-elected.
He ran as a Liberal candidate in 1953 in the district of Trois-Rivières and in 1958 in the district of Champlain. Each time he lost.
He won as an Independent candidate in the district of Trois-Rivières in the 1965 federal election. He was re-elected in 1968 as a Liberal.
Mongrain died in office on December 23, 1970.