James Derrick Slater (born March 13, 1929) is an investor.

Trained as a chartered accountant, he worked for Leyland Motors and became famous for writing an investment column in The Sunday Telegraph under the nom de plume of The Capitalist, where he described his own portfolio. In 1964 he started an investment company with Peter Walker, a Tory MP, called Slater Walker—in actuality an authorized bank. He performed what became known as corporate raids on public companies. He was a friend and business associate of James Goldsmith.

During the secondary banking crisis in 1975, Slater Walker received support from the Bank of England. Following the takeover of the Company by the Bank of England 15 charges were brought against Slater for offences against the Companies Act by the Department of Trade—the misuse of more than £4,000,000 of company funds in share deals. The case was thrown out in 1977.