4. Terrell Williams, Lions defensive line coach/run game coordinator
The litany of injuries the Lions have had along the defensive line this season have surely tested Williams as a coach, and look no further than the performance of Al-Quadin Muhammad on Thanksgiving Day against the Bears (five pressures, one sack) as a fresh testament of his ability to coach players up.
In a bit of an odyssey, given how long he's been in coaching, Williams has only been a defensive line coach and never a defensive coordinator. He did take on the extra title of assistant head coach under Mike Vrabel with the Tennessee Titans in 2023 though, and he was the head coach of one of the teams at the 2024 Senior Bowl.
As internal candidates to replace Glenn go, Williams might be No. 1 if not for someone else on this list.
3. Robert Saleh, former New York Jets head coach
Saleh was clearly not the biggest problem with the Jets this season, even if he was the first fall guy. Since he was fired after a 2-3 start to the season, the Jets are 1-5 entering Week 13 and their defense has been noticeably worse (25 or more points allowed four times in six games).
Saleh, a Dearborn, Michigan native, was in the mix for the Lions' head coaching job before Campbell was hired. Bypassing him proved to be a good decision, of course, but the issues the Jets' had during his tenure almost entirely lied with the offense and failing to find a suitable quarterback. And one offensive coordinator hire (Nathaniel Hackett) was hoisted on him to appease Aaron Rodgers.
Saleh is currently working as a consultant with the Green Bay Packers, and he will surely be in the mix for defensive coordinator posts after the season. If the Lions are in the market for a new one, he's an easy candidate.