I can do no better to start with than the part of the rec.sport.pro-wrestling FAQ that covers the NWO, maintained by Scott Keith:

nWo 0.9, May 1996: Scott Hall appears on Nitro promising a "takeover". The next week, Kevin Nash appears and promises the same thing. They attack people for the next month or so (most notably powerbombing Eric Bischoff through a table) until challenged by Sting, Lex Luger, and Randy Savage to a six-man tag at Bash at the Beach. Nash and Hall - at this point only "The Outsiders" - accept, and say their third man will be revealed later.

nWo 1.0, July - August 1996: Hall and Nash are victorious when their third man is revealed to be Hulk Hogan, who over time adopts the new persona of "Hollywood" Hogan. The newly-christened New World Order begins attacking WCW wrestlers viciously. The first new members to arrive are Ted DiBiase (acting as a manager and "money man") and Vincent (acting as "head of security"). At Road Wild, Hollywood Hogan defeats the Giant by cheating outrageously to win the WCW World title. Strangely, the Giant joins the nWo two weeks later, citing the money as his primary reason. Also at Road Wild, the Booty Man tries to join, but is beaten up.

n Wo 1.1, September - November 1996: The next member of the nWo appears when they debut a "Fake Sting" at Wargames, who wrestles ittermitently over the next few months until the original Fake Sting, now called "nWo Sting", goes to compete in Japan as part of their version of the nWo. The Nasty Boys try to join the nWo as well, but are beaten up for their trouble. Although he is in fact the seventh member, Sean Waltman joins in November as Syxx.

nWo 1.2, December 1996 - January 1997: The nWo announces a "membership drive", giving "all WCW wrestlers" the chance to join the nWo. In order, the wrestlers accepting this offer are Marcus Bagwell (soon redubbed "Buff"), Michael Wallstreet, Big Bubba, and Scott Norton. Also, Eric Bischoff is revealed as being an nWo member around this time, and Masa Chono and the Great Muta, visiting from New Japan Pro Wrestling, join the North American nWo (although they have little effect). At the same time, Giant is kicked out for demanding a title shot from Hulk Hogan.

nWo 1.3, Feburary - August 1997: Randy Savage joins the nWo at SuperBrawl. Newly appointed WCW Commissioner J.J. Dillon says that according to their contracts, Big Bubba and Michael Wallstreet cannot be members of the nWo. Amidst great hype, Dennis Rodman "joins" the nWo, despite wrestling only one match that year as a celebrity guest at Bash at the Beach. Konnan joins the nWo in August. Ted DiBiase quits the nWo and becomes a manager for the Steiner brothers.

nWo 1.4, September 1997 - February 1998: Curt Hennig joins the nWo after turning on the Four Horsemen at WarGames. Rick Rude joins in December. Bret Hart is invited to join the nWo, but declines. The Disciple joins sometime in January, although he is not named until March. Dusty Rhodes joins at Souled Out after turning on Larry Zybysko. Bryan Adams joins in January after turning on Bret Hart. Scott Steiner joins in February after turning on his brother Rick. During most of January, Louie Spicolli acts as a flunky to Scott Hall and wears an nWo t-shirt, although he is never "officially" inducted into the nWo before his death. Syxx disappears when Sean Waltman is fired by WCW.

nWo 2.0, February - April 1998: Randy Savage and Kevin Nash, having issues with Hollywood Hogan, form the nWo "splinter faction": nWo Wolfpac. Curt Hennig and Konnan immediately join, as do longtime nWo foes Lex Luger and Sting; they immediately distinguish themselves from the "traditional" nWo (now known as nWo Hollywood or nWo Black-And-White) by wearing black-and-red T-shirts rather than black-and-white. Scott Halll is invited to join the Wolfpac, but refuses. Giant rejoins nWo Hollywood.

nWo 2.1, May - October 1998: Curt Hennig quits the nWo Wolfpac to rejoin nWo Hollywood. Randy Savage is injured and disappears from the Wolfpac. Dennis Rodman once again is trumpeted as a member of the nWo for a celebrity match at Bash At The Beach. Stevie Ray joins nWo Hollywood in September. The Disciple quits nWo Hollywood in October to join the "One Warrior Nation". Horace Hogan joins nWo Hollywood at Halloween Havoc. Bret Hart seemingly joins, quits, and rejoins nWo Hollywood several times during this period, and never wears an nWo shirt or explicitly states his membership in the nWo.

nWo 2.2, November - December 1998: Hollywood Hogan announces his "retirement", and Scott Steiner becomes the leader of nWo Hollywood. Scott Hall is kicked out of nWo Hollywood in November, but despite his efforts is not allowed to join nWo Wolfpac. Disco Inferno starts claiming he is a member of the Wolfpac.

nWo 3.0, January 1999 - March 1999: Hollywood Hogan comes out of "retirement" to "beat" Kevin Nash in a thrown match for the WCW World title and reform the nWo as one single entity. The Wolfpac is now an "elite rank" of the nWo: its members are Hollywood Hogan, Kevin Nash, Scott Hall, Lex Luger, Buff Bagwell, and Scott Steiner. The remainder of the nWo (Giant, Curt Hennig, Vincent, Stevie Ray, Bryan Adams, Scott Norton, and Horace Hogan) continues wearing the black-and-white, while the Wolfpac wears black, white, and red. The Wolfpac also seems to be conducting a gradual elimination of the black-and-white (also referred to as "the nWo B-Team"); at this writing, both the Giant and Curt Hennig have received turfing-out beatdowns, with more likely to come. Konnan has been explicitly kicked out of the nWo entire. Sting's status is unknown. Bret Hart's nWo membership is entirely forgotten.

nWo 3.1, April 1999 - onward: With Scott Hall in retirement, Hulk Hogan back in semi-retirement, and Bagwell turfed from the group, the only members left are Lex Luger, Kevin Nash and Scott Steiner, and possibly Disco Inferno. Steiner and Nash rarely do anything nWo-related (besides use the Wolfpac music). The nWo black-and-white is whittled down to Vincent, Horace Hogan, Stevie Ray and Bryan Adams, with Scott Norton doing his own thing without the nWo name. Soon after, Horace Hogan is fired, Bryan Adams is repackaged, Stevie Ray leaves to reform Harlem Heat, and Vincent joins the West Texas Rednecks, thus finally ending the group’s legacy once and for all.


My only additions: The nWo made a brief return in late 1999 in the form of Kevin Nash, Scott Hall, Jeff Jarrett, and the returning Bret Hart. It largely fell apart after a few months due to Scott Hall being suspended from WCW (for the upteenth time) and Bret Hart leaving the active roster due to injury. It now does appear as if the nWo is finally dead after all.

The people who can be credited with coming up with the nWo angle were Paul Orndorff, who thought up the initial "invasion" angle, and Terry Taylor, who came up with most of the "details"--t-shirts, colors, etc. Whatever he may claim, Eric Bischoff had almost nothing to do with it. :)