| Honorific-Prefix: | The Honourable |
| T. William L. Prowse | |
| Order: | 17th |
| Office: | Lieutenant Governor of Prince Edward Island |
| Term Start: | October 4, 1950 |
| Term End: | March 31, 1958 |
| Predecessor: | Joseph Alphonsus Bernard |
| Successor: | Frederick Walter Hyndman |
| Governor General: | The Viscount Alexander of Tunis Vincent Massey |
| Premier: | J. Walter Jones Alex W. Matheson |
| Office1: | MLA (Assemblyman) for 5th Queens |
| Predecessor1: | W. Allen Stewart |
| Successor1: | W. F. Alan Stewart |
| Term Start1: | July 23, 1935 |
| Term End1: | May 18, 1939 |
| Predecessor2: | W. F. Alan Stewart |
| Successor2: | David L. Matheson |
| Term Start2: | September 15, 1943 |
| Term End2: | December 11, 1947 |
| Order3: | 26th |
| Office3: | Mayor of Charlottetown |
| Predecessor3: | Ira J. Yeo |
| Successor3: | William S. Stewart |
| Term Start3: | 1930 |
| Term End3: | 1932 |
| Birth Date: | 31 August 1888 |
| Birth Place: | Charlottetown, Prince Edward Island |
| Death Place: | Charlottetown, Prince Edward Island |
| Nationality: | Canadian |
| Party: | Liberal |
| Relations: | Lemuel Ezra Prowse (father) |
| Children: | Lemuel E., Doris H., Margaret F., and Fairlie C. |
| Residence: | Charlottetown, Prince Edward Island |
| Alma Mater: | Sydney Academy Prince of Wales College |
| Occupation: | Businessman |
| Profession: | Politician |
| Cabinet: | Minister without Portfolio (1935-1939)(1943-1947) |
Thomas William Lemuel Prowse (August 31, 1888 – November 2, 1973) was a businessman and was the 17th Lieutenant Governor of Prince Edward Island from 1950 to 1958.
The son of Lemuel Ezra Prowse and Frances J. Stanley, he was born and educated in Charlottetown, Prince Edward Island.
He was proprietor and president of Prowse Brothers Ltd. in Charlottetown. Active in local politics, he was a councillor on Charlottetown City Council for eight years and served as the 26th mayor from 1930 to 1932.
A Liberal, he was elected to the Legislative Assembly of Prince Edward Island representing the Charlottetown Common and Royalty District in Queens County, first in the 1935 general election and again in 1943. In 1950 he was appointed lieutenant governor of the island and served for eight years.