Tatiana Auguste (born 2001) is a Canadian politician who served as the member of Parliament (MP) for Terrebonne from 2025 to 2026. Elected in the 2025 federal election by one vote as a member of the Liberal Party of Canada, her election was annulled by the Supreme Court of Canada on February 13, 2026, leaving the seat vacant until a by-election is held.
Auguste was born in Port-au-Prince, Haiti in 2001. Her family immigrated to Canada in 2008, settling in Montreal. She studied economics at Concordia University, afterward working as an e-commerce consultant for the Fédération des chambres de commerce du Québec. Auguste also worked as an assistant to Bourassa MP Emmanuel Dubourg.
Auguste ran as the Liberal candidate for the riding of Terrebonne in the 2025 federal election. She was initially thought to have defeated incumbent Bloc Québécois MP Nathalie Sinclair-Desgagné by 35 votes in the initial vote count. However, subsequent validation of the count by Elections Canada instead showed that Sinclair-Desgagné had retained her seat by a 44-vote margin. Due to the tight margin, an automatic recount was called. On May 10, 2025, the judicial recount in the Superior Court of Quebec flipped the seat back to Auguste by the margin of a single vote, the narrowest result in the country. She was one of four people born in the 21st century elected to the House of Commons in the 2025 election. Auguste called the experience "a rollercoaster. From winning to not winning, and then winning again."
On May 13, a Bloc Québécois voter disclosed that her mail-in ballot had been returned to her due to a postal code misprint on the envelope provided by Elections Canada. After Elections Canada said that it did not have legal standing to change the result, the Bloc Québécois announced on May 15 that it would seek a court order for a new by-election. The same day, Elections Canada stated that five other mail ballots with the incorrect returning address printed had been rejected because they had arrived at the Elections Canada office in the riding after the deadline; the statement said that it could not determine if the incorrect address was responsible. The election result was upheld on October 27 by the Superior Court of Quebec. On November 3, Sinclair-Desgagné announced that she would be appealing the ruling to the Supreme Court of Canada. On February 13, 2026, the Supreme Court annulled the result of the election in the riding, leaving the seat vacant until a by-election is held.