The Watchtower Bible and Tract Society was born in dissent. Charles Taze Russell, its founder, (was a Presbyterian, then a Congregationalist, then a skeptic, then an Adventist, and finally originated his own brand). See http://watchtower.observer.org/
and click on "Russell" in the left panel under "History." His followers were known as Russellites or Millennial Dawners. Still later they became known as International Bible Students. Finally, in 1931 they took on the name Jehovah's witnesses.
The following is a list of splinter groups from the Watchtower Society. So much for unity! How many do you recognize?
Bible Studies Fellowship, headquarters in San Diego, Ca.
Bible Way Publications, Ft. Lauderdale, Fl.
Christian Millennial Fellowship, Hartford, Conn. Publishes the New Creation magazine.
Christian Renewal Ministry, Saratoga, Ca.
Church of God of Abraham, Wenatchee, Wa. Publishes Notes for Bible Students newsletter
Dawn Bible Students, East Rutherford, N.J. One of the original splinter groups formed after Joseph Rutherford became president of
the Watchtower Society
Fort Worth Bible Students, Ft. Worth, Tx. Republishes older W.T. Society literature
Laodicean Home Missionary, John Krewson, Ft. Myers, Fl.
Laymen's Home Missionary Movement, Raymond Jolly, Chester Springs, Pa. Publishes the Bible Standard and Herald of Christ's
Kingdom newsletter. {In turn, a splinter group came out of this group: Epiphany Bible Students Association, Mount Dora, Fl.
Publishes a newsletter under the group's name}
Pastoral Bible Institute, Milwaukee, Wisconsin
There is a group under Hayiland Davis, Albany, N.Y. I'm not sure of the name.
In Africa there is a group that originated in the 1920s called Kitawala Movement.
If anyone knows of other groups, please feel free to include them.