Pseudonym: Playdon, William D.
"Playdon" is identified by CIA to HSCA as short for "William D. Playdon", which is identified as a pseudonym.
Tracy Barnes is identified as "(Playdon, William D.), Chief of the Political and Psychological Staff, Directorate of Plans, Central Intelligence Agency".
Lander, OSS, p. 230: http://lander.odessa.ua/doc/OSS%20-%20The%20Secret%20History%20of%20America's%20First%20Central%20Intelligence%20Agency.pdf
"Barnes was a young attorney at the War Production Board, educated at Harvard and Yale, who had completed two SO missions behind the lines in France...Barnes was CIA base chief in Frankfurt, 1954-1956, and station chief in London, 1957-59. He was CIA liaison with the State Department during the Bay of Pigs operation, then became chief of the agency's so-called Domestic Operations Divsion. He resigned from the government in 1968 to become special assistant to the President of Yale University (note: Kingman Brewster)." Also note that Kingman Brewster was supportive of the Black Panthers and opposed to the Vietnam War - see Geoffrey Kabaservice, "The Guardians" (Owl Books, 2005) at p. 421: Henry Kissinger "mused aloud that Brewster was the one man whose assassination would benefit the United States."