"I'm very appreciative for the 10 years of loyal service that Glenn Spencer gave to Oklahoma State," Cowboys head coach Mike Gundy said in a brief statement.
Spencer began coaching at Oklahoma State in 2008 as a defensive line coach. He served as co-defensive coordinator in 2011 and 2012 and was named the sole defensive coordinator January 2013.
The Cowboys were ranked 14th in final AP poll after beating Virginia Tech 30-21 in the Camping World Bowl.
Oklahoma State ranked 85th nationally in scoring defense, allowing 29.4 points per game, but that was good enough to rank sixth in the Big 12.
--LSU promoted tight ends coach Steve Ensminger to offensive coordinator, the school announced.
Ensminger served as interim offensive coordinator for eight games in 2016 after head coach Ed Orgeron replaced Les Miles. The 59-year-old Ensminger returned to his previous position under coordinator Matt Canada in 2017, but Canada and LSU parted ways after the bowl loss to Notre Dame.
--Clemson left tackle Mitch Hyatt, projected as a possible second-round selection by NFLDraftScout.com, has decided to return for his senior season.
Hyatt is a two-time first-team All-ACC selection, and he won the ACC's Jacobs Blocking Trophy, given to the top offensive lineman in the ACC as voted on by the league defensive coaches.
--Ohio State wide receiver Parris Campbell has decided to return for one more season with the Buckeyes rather than enter the NFL Draft.
Campbell announced his decision on Twitter.
Campbell is ranked as the No. 9 wide receiver prospect in the NFL class of 2019 by NFLDraftScout.com.
--Scott Frost was named the Bear Bryant Coach of the Year recipient, marking his fifth major national coach of the year award.
The current Nebraska coach led Central Florida to a 13-0 record and a 34-27 victory over Auburn in the Peach Bowl on Jan. 1. The impressive turnaround came on the heels of taking over a Knights club that posted an 0-12 mark the year before his arrival.
--Former South Carolina running back Marcus Lattimore is returning to his alma mater.
Lattimore, whose NFL career failed to get off the ground after a pair of serious knee injuries in college, will serve as the Gamecocks' director of player development for life skills.
--Florida coach Dan Mullen filled out his coaching staff by naming Ron English his safeties coach.
English spent last season working with Mullen at Mississippi State after serving as the defensive coordinator for San Jose State in 2016.
However, English was fired during his fifth season at Eastern Michigan in November 2013 under controversial circumstances. He was dismissed after a video surfaced of him using "wholly inappropriate language" while addressing the team.