Kevin Thomas Duffy (born January 10, 1933) is an American lawyer and former judge of the United States District Court for the Southern District of New York. He retired from the bench on September 30, 2016.
Born in New York, New York. He received an A.B. degree from Fordham College in 1954 and a LL.B. from the Fordham University School of Law in 1958. He clerked for J. Edward Lumbard at the Second Circuit Court of Appeals (1955–1958).
Duffy served as an Assistant United States Attorney (1958–1959) and assistant chief of the Criminal Division (1959–1961) at the office of the United States Attorney for the Southern District of New York before going into private practice as an associate with the New York City firm Whitman, Ransom & Coulson (1961–1966). He later became a partner with Gordon & Gordon (1966–1969). Duffy later appointed New York regional administrator of the Securities and Exchange Commission office (1969–1972). His tenure as Regional Administrator of the United States Securities and Exchange Commission was in a time of turmoil in Wall Street. He is viewed by many as having been the first proponent within the Commission of what eventually became Securities Investor Protection Corporation or SIPC.