| Honorific-Prefix: | The Hon. |
| Léonard Tremblay | |
| Birthname: | Léonard-David Sweezey Tremblay |
| Birth Date: | 1896 4, df=yes |
| Birth Place: | Chicoutimi, Quebec, Canada |
| Spouse: | Beatrice Cote m. 17 May 1920[1] |
| Constituency Mp: | Dorchester |
| Parliament: | Canadian |
| Predecessor: | Onésime Gagnon |
| Successor: | Robert Perron |
| Term Start: | October 14, 1935 |
| Term End: | June 11, 1953 |
| Office2: | Senator for Lauzon, Quebec |
| Appointed2: | Louis St. Laurent |
| Predecessor2: | Eugène Paquet |
| Term Start2: | June 12, 1953 |
| Term End2: | September 2, 1965 |
| Profession: | journalist, public servant |
| Party: | Liberal |
Léonard-David Sweezey Tremblay (16 April 1896 – 19 September 1968) was a Liberal party member of the House of Commons of Canada. He was born in Chicoutimi, Quebec and became a journalist and public servant by career.
Tremblay was educated at Lauzon College and served in both World War I and World War II. He was first elected to Parliament at the Dorchester riding in the 1935 general election then re-elected there in 1940, 1945 and 1949. The margin of victory of the 1949 election was particularly small, as Progressive Conservative candidate Gérard Corriveau trailed by 221 votes.[2]
At the end of the 21st Canadian Parliament in June 1953, Tremblay was appointed to the Senate under the Lauzon division and remained in the Senate until September 1965.