The Lions are already preparing for the real possibility that defensive coordinator Aaron Glenn could be on his way out.
Glenn is one of the top head coach candidates in the NFL after four seasons as DC in Detroit. He’s already interviewed for multiple vacancies including the Bears, Jets and Saints.
Regardless of where Glenn goes, the Lions will need to have a replacement lined up to keep their momentum going in this “Brand New Lions” era of football in Detroit.
Let’s take a look at possible replacements.
Kelvin Sheppard
Assuming Glenn doesn’t take him with him to his next destination, Kelvin Sheppard would be an obvious choice to take over as the next Lions defensive coordinator.
“I think Shep is a young, promising coach. I think he can be a coordinator one day, and I think he can be a head coach one day,” head coach Dan Campbell said in 2023. “I think he’s got that type of potential, so the time is right.”
Sheppard came to Detroit in 2021 as an outside linebackers coach, coming into a dire situation at the position for the defense. During his time as coach, the team invested heavily in its linebackers, drafting Malcolm Rodriguez and Jack Campbell, and pushing veteran Alex Anzalone into a vital role for the unit.
Sheppard fits the mold that Dan Campbell has put in place for his defense, making him the most natural replacement for Glenn.
Dennis Allen
Dennis Allen didn’t have the success he’d hoped for in his two stints as an NFL head coach. The Saints fired Allen before the end of his third season.
Allen has a combined record of 26-53 as a head coach including his time in New Orleans and Oakland. However, his previous work as a defensive coordinator and his history working with Dan Campbell when Campbell coached tight ends for the Saints puts him on the radar for the team’s potential search to replace Aaron Glenn.
Allen has more than two decades of coaching experience in the NFL, leading most other candidates in that regard.
Terrell Williams
The Lions could choose to keep their defensive coordinator in house still by hiring run game coordinator/defensive line coach Terrell Williams.
Williams came to Detroit in 2023 after six seasons as defensive line coach with the Tennessee Titans. From 2018-23, Williams’s unit ranked fourth in the league with 10,044 rushing yards allowed over that span.
He would bring several years of experience at both the professional and collegiate levels to the table, and would be expected to retain the same culture that has driven the Detroit defense to keep up with its high-powered offense.
Jim O’Neil
Climbing down the Lions’ defensive ladder would naturally bring the team to Jim O’Neil.
O’Neil joined the Lions in 2024 as a defensive assistant after several years of bouncing between various roles in the NFL and college. He’s been a defensive coordinator for Northwestern (2021-22), the 49ers (2016) and the Browns (2014-15).
While O’Neil has plenty of experience, he doesn’t have a track record of longevity in any of his previous roles. He has the advantage of being in-house already, but his track record on paper would likely rank him below some of the candidates mentioned earlier.
Honorable Mentions
There are a handful of other long-shot possibilities out there, but they would certainly be surprising hires.
Former Jets head coach Robert Salah, current Michigan Wolverines defensive coordinator Wink Martindale, and veteran NFL DC Steve Wilks.
Those three are among the top names in the league for open coordinator positions, but none of them feel as though they’d fit the direction this Lions franchise is headed.
It’s more than likely they keep Aaron Glenn’s replacement in-house if possible as they aim to keep the culture they’ve built strong for years to come with a defense that would, in theory, be healthier and more talented next season.
