John Tan Thoon Lip (22 February 1910 – 14 March 1959) was a Singaporean lawyer and the first locally-born registrar of the Supreme Court.

[6][9] On 8 August 1930, Tan left Singapore for England on SS Kalyan, and enrolled in St. John's College to study law.

[15] Shortly after, on 1 March 1937, Tan was transferred back to Singapore to be appointed as the first Chinese locally-born magistrate.

[5][16] During the Japanese occupation of Singapore, Tan worked in the Office of the Custodian of Enemy Property, but was soon arrested in late 1942.

[22] Tan was also sent to New South Wales by Chief Minister David Marshall to study the free legal aid system, and the Free Legal Aid Bill was passed on 6 June 1956 based on recommendations provided by Tan.