Dame Judith Mayhew, Mrs. Jonas, DBE (born 1950) is a New Zealand-born British lawyer and academic.
Born and educated in New Zealand, Judith Mayhew graduated LLM from the University of Otago, where she lectured before moving to the UK as a lecturer in law at King's College London where she set up and became Director of the Anglo French Law Degree (Sorbonne), the first joint degree in Europe. In 1989, she entered private practice as an employment lawyer, rising to become Special Adviser to the Chairman at Clifford Chance, the world's largest law firm, before resigning to concentrate on her other roles. In 2006 she was appointed to the Board of Directors of Merrill Lynch.
She served as Provost of King's College, Cambridge from 2003-2005. She has also been closely involved in the running of the City of London since 1986. She was awarded the DBE in 2002 "for services to the City of London".
She was the first woman to become not only Chairman of the Royal Opera House, but also from 1996–2003, as Chairman of the Policy and Resources Committee, she was effectively leader of the City of London Corporation. She has also served on a number of boards of educational and cultural institutions in recent years, including Birkbeck, University of London & Imperial College London. She remains on the board of Gresham College, is a Trustee of the Natural History Museum, and a Vice President of London First. She was also awarded an honorary doctorate by the University of Otago in 1998. In 2004 she was made New Zealander of the Year in Britain. In 2008 she became Provost of Bishop Grosseteste University College Lincoln.