Ba Gua Zhang
The creator of Ba Gua Zhang was Dong Haichaun. He was born in Wen An County in Hebei perhaps in 1813 although some claim his birth to be as early as 1796. He passed away in 1882. As a young man he was locally famous for his martial arts. However it is not clear exactly which arts he knew. It may have been some local form of Shaolin long fist. Dong may also have learned an art called Pa Fan (eight revolving fist) from one of his relatives in the same county. Pa Fan was known for its palm strikes and many of it's movements and techniques can be found in Ba Gua. He traveled to the eastern provinces of China researching martial arts in Jiangsu, Anhui, and Zhejian and then west to the middle of the country, Sichuan and Shaanxi. Eventually he became a member of the Complete Truth, Chuan Chen, sect (who wouldn't want to know the complete truth!) of the Dragon Gate, Lung Men, school of Daoism. This sect utilized circle walking meditation while repeating a mantra to unify body, mind and spirit. Most researchers believe that from this practice he created his own unique art.
Dong Haichaun was always vague about how he learned his art. When asked, he would claim to have learned it from a "Daoist in the mountains". This may be because he felt that people would not appreciate the art if they knew he created it himself. Of course it is in the old tradition of China to attribute something new to some old and mysterious (or famous) person in the past. The same thing is true of Xingyi when it is attributed to General Yue Fei or Taiji when they invoke Zhang Sanfeng as their founder. There are also some people who insist that he learned his art from the Daoist master Bi Den Xia on Nine Flower Mountain in Anhui. It does seem to me that since Dong Haichaun created Ba Gua based on circle walking meditation and he said that walking the circle was superior to any technique, one could say, in a sense, that he did learn it from a "Daoist in the mountains".
After he moved to Beijing he became very famous for his martial skill and was appointed instructor for the imperial guard in the palace of Prince Su. The circumstances of his ending up in the Palace are cloudy. One story is that he was made a eunuch in order to work there or as punishment for some offence. (Li Ziming believed this to be true) However, contemporary accounts of him always refer to his strong build, which would seem odd in a eunuch. A commonly repeated story is that in order to escape people who were out to do him harm he entered the service of Prince Su. While serving food at a banquet (any actor reading this will appreciate that he was a waiter) the Prince noticed how deftly he moved through the large crowd and seeing that he must have some martial skill he ordered Dong Haichaun to perform his art. He complied and the Prince was so impressed that he had him appointed as a martial arts instructor in the palace. However Dong Haichaun apparently did not teach Ba Gua in the beginning. Instead he taught Long Fist. Later he taught what he called "Rotating Palm" and sometimes "Swimming Dragon Palm" and it was only later in his life that he called it Ba Gua Zhang, eight trigram palm.
Dong Haichaun taught only experienced martial artists and it seems he adapted his art to fit each students skill set. The basic circle walking, single and double palm change, and body turning palm were taught to everyone. Later the changes (which all derive from the first three palms) would be flavored by the art that the student already knew. This led to many interpretations of Ba Gua. In fact it is quite difficult to sort out what he actually taught from what was added by his students. Of course everyone likes to claim that their style is the "original" style, but I think all of his disciples brought their own interpretation to the art. Since they themselves were highly accomplished martial artists that is not a bad thing at all. Indeed it has helped the art to grow and flourish. Of course the other side of the coin is that Ba Gua can become so complex that, as Wang Xiangzhai said, "everyone can do the sixty four palms but only a few can do the single change palm." People spend so much time learning all of the many techniques and forms of Ba Gua that they fail to develop the Shen Fa (body movement) that will actually make it all work.