| Theobald Butler Barrett | |
| Constituency Mp: | Norfolk |
| Parliament: | Canadian |
| Predecessor: | William Horace Taylor |
| Successor: | Raymond Elmer Anderson |
| Term Start: | 1945 |
| Term End: | 1949 |
| Birth Date: | July 24, 1894 |
| Birth Place: | Armstrong, British Columbia, Canada |
| Death Place: | Port Dover, Ontario, Canada |
| Nationality: | Canadian |
| Party: | Progressive Conservative |
| Occupation: | farmer |
Theobald Butler Barrett (July 24, 1894 – March 26, 1969) was a Canadian politician. He was elected to the House of Commons of Canada in 1945 as a Member of the Progressive Conservative Party of Canada to represent the riding of Norfolk. He was defeated in the 1949 election. Prior to his federal political experience, he was a Lieutenant in the Royal Canadian Artillery between 1942 and 1943.
Barrett was the grandfather of Toby Barrett, Member of the Ontario Provincial Parliament for Haldimand—Norfolk from 1995 to 2022.