Frank W. Dux (pronounced "dukes"; born 1956) is an American martial artist and fight choreographer. Dux established his own school of Ninjutsu in 1975, called "Dux Ryu Ninjutsu". He is also notable as the inspiration of the 1988 film Bloodsport starring Jean-Claude Van Damme. Dux has been a controversial figure in martial arts, and the validity of many of his personal claims has been disputed.
Dux states that he was introduced to and trained in Koga Yamabushi "Ninjitsu" by Senzo "Tiger" Tanaka, beginning at age 13. In the 1970s, Dux began teaching Dux Ryu Ninjitsu. He opened his first school in Hollywood in 1980 while subsequent schools have been owned and operated by his students. Dux and his students have coached and produced a number of boxing and martial art regional, national, and world champions.
Dux has introduced, choreographed, and trained many of his students for the entertainment industry. One of Dux's first students to achieve a black belt, Stuart Wilson, has performed as an actor/stuntman in various film projects since 1990's Lionheart.
Dux's martial art style "Dux Ryu Ninjitsu" is not a “koryu” 15th century feudal form of Ninjutsu, but is still claimed to be "based on its Koga Ninja root principles of adaptability and consistent change." Frank Dux formulated the proprietary augmentation technology he calls DUX FASST (Focus-Action-Skill-Strategy-Tactics).
Dux has written an autobiography entitled The Secret Man: An American Warrior's Uncensored Story. Dux was the inspiration for, and co-wrote, the 1988 motion picture Bloodsport, and also served as fight choreographer. The film featured Jean Claude Van Damme who portrayed Frank Dux. The film has been described by Dave Carter of Inside Kung Fu Presents The Complete Guide To Ninja Training as the "Ultimate Movie of the Ultimate Martial Art Contest".Dux also received co-writing credit for another Van Damme film, The Quest.
Dux has been a controversial figure in the martial arts community. The validity of many of his personal claims have been disputed. His claims concerning his martial arts background, fighting in the "Kumite", and prior military service have been alleged as unsubstantiated by the Los Angeles Times, Soldier of Fortune, and various former associates.