Katherine Barrett Wilson (born July 12, 1982) is an American politician and activist who serves as the 58th mayor of Seattle since 2026, having narrowly defeated incumbent Bruce Harrell in the 2025 election. A democratic socialist and co-founder of the Transit Riders Union (TRU), Wilson's activism has centered on public transit equity, workers' rights, and affordable housing—leading to key achievements like the ORCA Lift low-income fare program and Seattle's JumpStart payroll tax. Raised in New York by evolutionary biologists, she studied physics and philosophy at Oxford before moving to Seattle in 2004, where she worked in various blue-collar jobs before turning to full-time advocacy in 2011. Her 2025 campaign, which topped the primary with 50.9% of the vote, prioritized housing, homelessness, and "Trump-proofing" the city from federal actions. Analysts likened her electoral coalition—built from renters, transit riders, and Democratic Socialists—to Zohran Mamdani's New York mayoral bid, highlighting a broader progressive shift in municipal politics.