As the 2025 head coaching cycle approaches, both Detroit Lions coordinators are emerging as top candidates. Defensive coordinator Aaron Glenn, in particular, appears more likely than offensive coordinator Ben Johnson to depart for a head coaching role after this season.
Glenn’s success in leading a Lions defense that has been hit hard by injuries only strengthens his resume for a head coaching job. He is expected to have multiple opportunities if he chooses to pursue them, though, like Johnson, he is likely to be selective and not leave the promising situation in Detroit unless it makes sense for his career.
Head coach Dan Campbell is also aware that his coaching staff might change, and losing Glenn to a head coaching position is a real concern. It’s likely that Campbell has been preparing for this possibility, potentially considering candidates for a new defensive coordinator in case Glenn leaves.
Campbell assembled a strong staff when he took over in Detroit, and he’s not one to be caught off-guard by potential departures. If Glenn does leave, presumably with clear communication about any head coaching offers he’s interested in, a replacement could be quickly appointed.
If Glenn does depart for a head coaching role after the season, here are four potential candidates to take over as the Lions’ defensive coordinator.
4. Terrell Williams, Lions Defensive Line Coach/Run Game Coordinator
The series of injuries to the Lions’ defensive line this season has undoubtedly tested Terrell Williams as a coach. His ability to develop players is evident, especially with Al-Quadin Muhammad’s standout performance on Thanksgiving Day against the Bears, where he recorded five pressures and a sack.
Despite his extensive coaching career, Williams has never held the title of defensive coordinator, having only served as a defensive line coach. However, he did take on the role of assistant head coach under Mike Vrabel with the Tennessee Titans in 2023, and also served as head coach of one of the teams at the 2024 Senior Bowl. Among internal candidates to replace Aaron Glenn, Williams might be the top choice, if not for another strong contender.
3. Robert Saleh, Former New York Jets Head Coach
Robert Saleh, who was fired as the Jets’ head coach after a 2-3 start this season, was not the primary issue with the team. Since his departure, the Jets have struggled, with a 1-5 record heading into Week 13 and a noticeable decline in their defense (allowing 25 or more points in four of six games).
A native of Dearborn, Michigan, Saleh was a candidate for the Lions’ head coaching position before Dan Campbell was hired, though Detroit’s decision to go with Campbell has worked out well. Saleh’s tenure with the Jets was marred by offensive struggles and quarterback issues, and the team’s offensive coordinator, Nathaniel Hackett, was hired to accommodate Aaron Rodgers. Saleh is now serving as a consultant for the Green Bay Packers and will likely be a sought-after candidate for defensive coordinator roles after the season. If the Lions are looking for a new defensive coordinator, Saleh would be a strong option.
2. Dennis Allen, Former New Orleans Saints Head Coach
Dennis Allen was let go by the New Orleans Saints after a promising 2-0 start to the season deteriorated into a 2-7 record. With a 26-53 overall record across parts of six seasons as a head coach, it seems his days leading a team are likely over. His tenure as a head coach at both the Saints and the Oakland Raiders raised questions about his suitability for the role.
However, Allen’s defensive expertise is unquestionable. As highlighted by Al Karsten of Pride of Detroit, Allen greatly improved the Saints’ defense during his time as defensive coordinator from 2015 to 2021. Under his leadership, New Orleans consistently ranked among the top defenses in the league. In fact, during Allen’s two full seasons as head coach (2022 and 2023), the Saints finished with a top-10 scoring defense.
Dan Campbell and Aaron Glenn both worked with Allen during their time in New Orleans from 2016 to 2020, which could make Allen a strong candidate to join the Lions’ staff if Glenn leaves. His familiarity with Campbell and the coaching staff, combined with his proven defensive acumen, would make Allen an attractive option for Detroit.
1. Kelvin Sheppard, Lions Linebackers Coach
Kelvin Sheppard has quickly become a rising star on the Lions’ coaching staff. Known for his work with an injury-depleted linebacker corps, Sheppard’s future appears bright, and he is considered a strong candidate for a head coaching position down the line. However, for that to happen, he would likely need to first serve as a defensive coordinator, which makes him a key candidate to replace Aaron Glenn if he takes a head coaching role.
Sheppard’s leadership and ability to develop players have been impressive, and should Glenn (or offensive coordinator Ben Johnson, if he moves to a head coaching role) leave, it’s likely that Campbell would do everything in his power to promote Sheppard to defensive coordinator. Given Sheppard’s connection to the team and the trust Campbell has in him, he stands as the most probable next defensive coordinator for the Lions.