#1 Nebraska vs. Oklahoma
Once Texas joined the Big XII in 1996, it drove a wedge between a rivalry that had defined the conference for three quarters of a century.
Bud Wilkinson was the first Oklahoma coach to put a dent into the rivalry and get the Sooners into a respectable position against Nebraska. The 1971 Game of the Century pitted #1 Nebraska against #2 Oklahoma, and at the time the Big 8 had the Top 3 teams in the country with Colorado at #3.
The game featured a Heisman Trophy winner in the Cornhuskers Johnny "The Jet" Rodgers, two hall of fame coaches in Bob Devaney and Chuck Fairbanks, and it was the only show in town and the game didn't disappoint with a Rodgers punt return touchdown
The rivalry will always be personified by the duels that Tom Osborne and Barry Switzer had in the 1970's and 1980's.
The teams won't play again after Saturday until 2029 and 2030, and the once Thanksgiving tradition has a hard time being renewed considering both participants will be playing in the near future in the two power conferences of college football: Big Ten and SEC.
#2 Penn State vs. Pitt
The Pennsylvania Classic is one of those all time rivalries that defined an era. Between 1976 and 1982, the winner of this rivalry went on to play for the national championship in three of those seasons.
The intensity of the rivalry includes significant death threats to both Joe Paterno and Chuck Fusina ahead of the 1976 contest, Penn State's 1981 epic comeback down 14-0 to Dan Marino's #1 Pitt Panthers the Nittany Lions scored 48 unanswered to beat Pitt, to Billy Owens pick-six in the 1987 edition that ended any shot of Penn State securing a large bowl bid.
They played their 100th meeting in 2019 and it came down to a red zone stand as time expired, there is no timeframe of either team playing again.
#3 The Backyard Brawl
When Pitt and West Virginia met in Week 1 of this season, it was an electric game capped by MJ Devonshire's pick six to give the Panthers a 38-31 victory.
The excitement for this game was high, the last time they played was in 2011 when the Mountaineers beat the Panthers 21-20, it set the attendance record for highest attended even in the city of Pittsburgh's history. When you consider the rich professional sports history of Pittsburgh and that includes Pittsburgh Steelers postseason games, that is very impressive.
Separated by 75 miles via Interstate 79, the rivalry has always been one of the most intense regional rivalries. With the teams scheduled to meet through 2025 and set another four game series between 2029-2032.
#4 The Bedlam Series
While historically Oklahoma absolutely dominates its instate rival Oklahoma 90-19-7, it is typically one of the most chippy and heated rivalries in the southwest. With the game currently scheduled through 2026, there is no guarantee that Bedlam will continue beyond that.
Both sides have said all the right things that they want to keep playing, but the logistics of a new SEC schedule for the Sooners it might be not be advantageous for them to play the Cowboys. On the other hand, because of the uncertainty of the Big XII conference as a whole, Oklahoma State's focus is on keeping their program relevant. They'll need to do that until they can either latch on to one of the two mega-conferences or be a central figure in a reconfigured Big XII/Pac-12.
#5 The Border War
This isn't a rivalry that has the marquee value of the Iron Bowl, The Game, or any other high profile rivalry, this is a rivalry built on hate. But dating back to the days when both Kansas and Missouri were in the Western Interstate University Football Association (WIUFA), the transition to the Missouri Valley Intercollegiate Athletic Association (MVIAA - which would be the foundation of the Big XII), this famous rivalry between Kansas and Missouri started has a lot of blood shed.
The showdowns on the football field for the fans and some of the first players on both teams were the sons of men who had fought each other on both sides of the conflict in Bleeding Kansas and later the Civil War. In the Border Showdown, the teams have played the second most times in FBS history have a renewal upcoming in 2025-2026 and 2031-2032, this is a game that needs to be played annually.