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Professor Walter Woon Cheong Ming (Chinese: 温长明; born September 12, 1956) is the Attorney-General of Singapore.

Born in Singapore, Professor Woon (who was educated at Raffles Institution) earned his LL.B. degree from the National University of Singapore (NUS), graduating in 1981 with first class honours. He also obtained an LL.M. first class honours degree from Cambridge University in 1983. He was called to the Singapore Bar in 1985. Professor Woon then served as Sub-Dean of the National University of Singapore Faculty of Law (1988 to 1991) and later as Vice-Dean (1991 to 1995). He served as Legal Adviser to the President and Council of Presidential Advisors from 1995 to 1997.

Professor Woon became a Nominated Member of Parliament (NMP) in Singapore from 1992 to 1996. In 1995, Professor Woon moved a private member’s bill, which Parliament passed to become the Maintenance of Parents Act. Professor Woon was Singapore's Ambassador to Germany (February 1998 to July 2003) and was concurrently accredited to Greece (March 2000 to July 2003). He then served as Singapore's Ambassador to Belgium with concurrent accreditation to the European Communities, the Netherlands, Luxembourg and the Holy See.

Woon was appointed to the post of Second Solicitor-General in 2006, and Solicitor-General in 2007. In 2007, he was appointed Senior Counsel. He was appointed Attorney-General on 11 April 2008.

He is married to Janis Goh and has two sons. Apart from his numerous legal writings, he is also a fiction author.