Power of Attorney for Thomas P. Kelly

Thomas P. Kelly, Chief Financial Officer of Xenon Pharmaceuticals Inc., has executed a Power of Attorney appointing Andrea DiFabio, Ilona Lo, and Nathaniel Adams as his attorneys-in-fact. This Power of Attorney authorizes them to prepare, execute, and file various SEC forms and documents on his behalf, including Form ID, Form 3, 4, and 5, Schedules 13D and 13G, and Forms 144. The attorneys-in-fact are also empowered to perform any necessary actions related to these filings. The Power of Attorney remains in effect until Kelly is no longer required to file these forms or until he revokes it in writing. The document was executed on October 15, 2025.