While the concept of fantasy sports has existed in some form since the end of World War II, fantasy sports did not really become a large hobby until 1980s.

The first fantasy sport seems to have been golf. According to Bill Parsons:

Wilfred Winkenbach devised fantasy golf in the latter part of the 1950s, in which each player selected a team of professional golfers and the person with the lowest combined total of stokes at the end of the tournament would win. Golf is a simple fantasy game to administer and keep tabs on, since you are concerned only with the scores of your team members without anything else to complicate it.

In the early 1960's there were systems of "tabletop baseball", the most famous of which is Strat-O-Matic (published by the company of the same name). In these games, special baseball cards where printed with statistical information garnered from previous seasons' performance and, based on the specific rules of the game. These games were quite popular and variations using football were created.

The first fantasy league seems to be the Greater Oakland Professional Pigskin Prognosticators League (GOPPPL). Founded by Winkerbach himself, the fantasy league followed the AFL, since Oakland was an AFL-affiliated city. In a history of the League, the initial league was composed of Winkerbach, several Oakland sports writers, employees of the team, and two season ticket holders. The other thing to note was that the league kept detailed records which were placed on the web in 2006.

Separate from the GOPPPL, the Baseball Seminar was a fantasy league created by William Gamson, a Harvard Sociologist in 1960 who had learned the game from his former job at the University of Michigan. Among the members of the league were Bob Sklar, an American Studies Professor. One of his students, Daniel Okrent, learned of the game through Sklar.

In 1980 Okrent, now a magazine writer/editor developed the "Rotisserie League" (so named because the meeting location was the La Rotisserie Francaise Restaurant in New York) which was a version of the Baseball Seminar. The main innovation of the game was, instead of using statistical information from past seasons, the Rotisserie league would draft players at the beginning of the seasons and have to make predictions and adjustments based on performance and circumstances (such as injury) that would befall a real baseball manager.

Other journalists were introduced to the game at this time and wrote about it at length during in 1981 since, due to the baseball strike of that year, there wasn't much to write about, especially given the height of the baseball season (June-August) where there is usually no other sport to talk about.

In March 1981, Dan Okrent wrote an essay about the Rotisserie League for Inside Sports called "The Year George Foster Wasn't Worth $36." The article included the rules of the game. Founders of the original Rotisserie league published a guide book starting in 1984.

Okrent, based on discussions with colleagues at USA Today, credits Rotisserie league baseball with much of USA Today's early success, since the paper provided much more detailed box scores than most competitors and eventually even created a special paper, "Baseball Weekly," that almost exclusively contained statistics and box scores.

Baseball's fascination with statistics helped fuel growth of the fantasy sports movement. The Bill James Baseball Abstract, while focused primarily on statistical analysis of baseball,  became a very popular tool for fantasy players as a way to predict player performance for the upcoming season. The 1982 edition was published by Ballantine Books and its success was at least partially responsible by growing fantasy interest

Bill James is regarded as the founder of SABRmetrics, a refined system of baseball statistics designed by the Society for American Baseball Research. These new statistics, which were designed to be a more accurate rating of a player's performance than the traditional statistics of RBI, Batting Average, and ERA, were embraced by fantasy players which helped to further fuel growth of the game.
 

Among the first high-profile experts were John Benson, Alex Patton and Ron Shandler. Patton released books of player values ans stats in 1989. In November of 1986, Ron Shandler published Baseball SuperSTATS. While initially a book of sabermetric analysis, it became used as a fantasy guide. John Benson started a book and 900 number baseball analysis service in the late 1980s.

By 1990, USA Today was estimating about 500,000 people were playing fantasy sports.

In 1993, USA Today included a weekly columnist on fantasy baseball, John Hunt, and he became perhaps the most visible writer in the industry before the rise of the Internet.Hunt started the first high-profile experts league, the League of Alternate Baseball Reality, which first included notables as Peter Gammons, Keith Olbermann, and Bill James.

Around the late 1980s, as fantasy baseball began to hit it big, fantasy football also emerged. The Fantasy Football Index was released in 1987. Fantasy Sports weekly, which covered several sports was released in 1989. Fantasy Football Weekly, a companion to Fantasy Baseball Weekly was released in 1992 to brisk sales in the 90s. 

The internet boom of the late 90s also provided a new model for fantasy sports, since the barrier to entry was much lower. Fantasy sports sites such as Commisioner.com, RotoNews,com, and RotoWire.com were created and it was at this point, in 1998 a trade group, the Fantasy Sports Trade Association, was formed.

These developments did not go unnoticed. in 1996, STATS, Inc., a provider of statistics to fantasy sports firms was sued by the NBA, who were trying to stop the company from distributing in game score information via a special wireless device created by Motorola. The court case was decided on appeal in favor of STATS, Inc. and  successfully argued sports statistics can be collected/transmitted by third parties.

The victory played a large part in defending other cases where sports leagues have tried to suppress live in-game information from their events being distributed by other outlets. This case also opened the door to common features such as real-time statistics.

Another high-profile case was the case involving CDM Sports, and the MLBAM (Major League Baseball Advanced Media), the 'internet wing' of Major League Baseball. CDM's parent company, CBC Media, was denied a new licensing agreement with the MLBAM, even though it had secured the rights from the Player's Association.

CBC filed suit arguing "right of publicity" laws did not apply to the statistics used in fantasy sports, since the player names were being used as a group, the players had assigned their publicity rights to the players association who then signed licensing deals.

As noted in an ESPN Article, the claim was:

"The names and playing records of major-league baseball players as used in CBC's fantasy games are not copyrightable," Medler wrote. "Therefore, federal copyright law does not pre-empt the players' claimed right of publicity."

The decision was found in favor of CBC Media in August of 2006. The 8th Circuit Court of Appeals upheld the decision in October 2007. "It would be strange law that a person would not have a First Amendment right to use information that is available to everyone," a three-judge panel said in its ruling. The U.S. Supreme Court upheld the 8th Circuit Court's decision by declining to hear the case in June 2008.

While not a court case, the passage of the Unlawful Internet Gambling act of 2006 is interesting because it enshrines fantasy sports as a legal online activity. The bill specifically exempts fantasy sports games, educational games, or any online contest that

"has an outcome that reflects the relative knowledge of the participants, or their skill at physical reaction or physical manipulation (but not chance), and, in the case of a fantasy or simulation sports game, has an outcome that is determined predominantly by accumulated statistical results of sporting events, including any non-participant's individual performances in such sporting events..."

Currently, Fantasy Sports takes up a section of most sports section in newspapers, on sports programming such as on ESPN's Sportscenter, and on sports websites. ESPN's page, for example has a "Regular" and "Fantasy" tab which allows users to quickly switch from sports reporting to fantasy related news. Fantasy Sports also encompasses a wide range of sports from Baseball and Football to cricket, soccer, and even the original fantasy sport, golf.

The Fantasy Sports Writers Association was formed in 2004 to represent the growing numbers of journalists covering fantasy sports exclusively. The Fantasy Sports Association was formed in 2006.