Dame Kathryn Mary Thirlwall, DBE (born 21 November 1957), styled The Rt Hon Lady Justice Thirlwall, is an English judge of the Court of Appeal, and from January 2020 to September 2021 was the Senior Presiding Judge for England and Wales.

[4] She then studied at the University of Bristol, graduating with a Bachelor of Arts (BA) degree in 1980.

[3] She studied for the Common Professional Examination, a qualification for those without a law degree, at Newcastle Polytechnic; she completed this in 1981.

She was appointed as a High Court judge in April 2010, assigned to the Queen's Bench Division, and received the customary damehood.

In September 2023, the UK government confirmed that she will lead the statutory inquiry into the case of Lucy Letby.