The Jeopardy! Battle of the Decades was a special 5-week tournament airing throughout the 30th season of the television game show Jeopardy! to commemorate the 30th anniversary of the daily syndicated version of the show, hosted by Alex Trebek. The tournament involved 45 previously successful Jeopardy! contestants split into three groups based on the time period of their initial appearance on the program.^[1] Though the groups roughly represented 1984-1993, 1994–2003, and 2004–2013, they were referred to as the 1980s, 1990s, and 2000s, respectively. The tournament's 1980s round began airing on February 3, 2014 with the tournament's final episode airing that year on May 16, covering 25 shows in total.^[2] The tournament's grand prize was US$1,000,000.^[1] Brad Rutter won the $1,000,000 cash prize, once again giving Rutter the highest game-show winnings in history.

The Battle of the Decades was conceived by Jeopardy! executive producer Harry Friedman. Knowing that the Trebek version was nearing its 30th anniversary, he and other producers of the program contacted every still-living Jeopardy! contestant who had ever participated in a Tournament of Champions to see if they would be interested in making another appearance on the program. The many people who expressed interest were asked to submit a video and an essay of several paragraphs, discussing why they should reappear.^[3] In the end, the list was narrowed down to 45 contestants, with 15 players from each "decade" the Trebek version had been airing.^[1]

For each "decade," one participant was selected by the viewers in an online poll on the show's Twitter account and official website, with the choices coming from a producer-created shortlist.^[4]

The tournament was played in four separate rounds. Three preliminary rounds were played, one per "decade"; in each round, the 15 participants from that "decade" competed against each other in a series of five games. Only the winner of each game advanced, while the other players received $5,000 each. The fourth and final round was played according to the show's traditional two-week tournament format, with a week of quarterfinal games between the 15 winners from the preliminary rounds. Each of these five games included one player from every "decade." The winners advanced, as did the four non-winners with the highest scores (the "wild card" positions). The nine remaining players competed in three semifinal games (though the decades were now ignored for the seeding), and only the winners advanced to the two-game final match. The finalists' scores over both games were added to determine the overall standings, with $1 million awarded for first place, $100,000 for second, and $50,000 for third. Players eliminated in the semifinals and quarterfinals received $25,000 and $10,000, respectively.

Contestants in the 1980s bracket of the tournament initially appeared on Jeopardy! from 1985 to 1993.^[5]

Contestants in the 1990s bracket of the tournament initially appeared on Jeopardy! from 1993 to 2002.^[5]

Contestants in the 2000s bracket of the tournament initially appeared on Jeopardy! from 2003 to 2012.^[5]

^1 Cooper, Whitlock, and Wenglinsky were selected as the standby players for the quarter-finals and were part of the traveling contingent for the quarter-finals taping. In Jeopardy! tournaments, standby players usually are the next highest scoring player on eligibility lists. For this tournament, one eliminated player from each of the 3 preliminary weeks was chosen by producers as the standby player.
^2 Politicians and political appointees are ineligible to participate on Jeopardy! Since Richard Cordray was director of the Consumer Financial Protection Bureau at the time of taping and broadcast of the show, he was ineligible to receive the $5,000 consolation prize all invitees who lost their preliminary game received. His winnings were not distributed to anyone. Unlike other contestants, Cordray paid his own way to participate in the Tournament.
^3 This contestant did not qualify to play Final Jeopardy! because he or she had a zero score at the end of Double Jeopardy!.
^4 This contestant did not qualify to play Final Jeopardy! because he or she finished Double Jeopardy! with a negative score.
^5 Vinita Kailasanth originally competed on Jeopardy! in 2001, which was part of the "1990s decade" for the first round groupings, but as her Tournament of Champions appearances weren't until 2004, she was included in the 2000s decade games.

• Official Jeopardy! website
• J! Archive - complete recaps of all BotD games