Thirlwall is a surname. Notable people with the surname include:

• Anthony Thirlwall (born 1941), Professor of Applied Economics at the University of Kent
  • Thirlwall's Law, a law of economics
• Connop Thirlwall (1797–1875), English clergyman and historian, Bishop of Saint David's
  • Thirlwall Prize, awarded at Cambridge University
• Jade Thirlwall (born 1992), an English singer
• William Thirlwall, English MP

• Thirlwall Castle, Northumberland, England
• Thelwall
• Thelwell