Wo Fat is the name of a fictional villain in the long-running CBS series Hawaii Five-O. He is the arch-nemesis of Steve McGarrett (Jack Lord), the head of Hawaii's (fictional) state police force, named "5-0" due to Hawaii being the fiftieth state admitted to the union. Wo Fat is a Red Chinese intelligence officer and a staunch communist. He appeared in eleven episodes of Hawaii Five-O including the TV-movie pilot and the final episode. Two of them were two-part episodes and three were two-hour specials later re-edited into two-parters for reruns. The series finale, Woe to Wo Fat was the character's first appearance in nearly four years. In it, the antagonist is depicted as an international super-criminal, more resembling Dr. Loveless of The Wild Wild West series than the Red Chinese intelligence figure as he had invariably been previously portrayed. Here, Wo Fat is finally arrested and jailed. However, in the final shot, he smiles and craftily produces a concealed key. It remains a perpetual cliffhanger.

Wo Fat was portrayed by actor Khigh Dheigh (born Kenneth Dickenson) who, despite looking sufficiently Asian for the role, was actually of mixed Anglo, Egyptian, and Sudanese ancestry.

In the first two-and-a-half years of the show's existence, Wo Fat made six appearances. However, presumably due to President Richard Nixon's visit to China in February 1972 and his talks with Mao Zedong that led to a period of détente between the two nations, his appearances after the historic event became far more sporadic: just five episodes in eight years.