Staff Directory
O'Brien, Grant
Grant O'Brien
- Title:
- Assistant Defensive Backs Coach
Grant O'Brien enters his first season as Northwestern's assistant defensive backs coach in 2025, bringing more than a decade of experience coaching in the secondary across the Big Ten and beyond.
O'Brien arrived in Evanston following two seasons as the safeties coach at Purdue, where he made an immediate impact on the Boilermakers' defense. In 2023, he was named Our Coaching Network's National Safeties Coach of the Year after mentoring standout freshman Dillon Thieneman to a record-breaking campaign. Under O'Brien's guidance, Thieneman became an AP Third-Team All-American, FWAA Defensive Freshman of the Year, and Big Ten Freshman of the Year, leading all FBS first-years in solo tackles and interceptions. Sanoussi Kane also thrived under O'Brien's direction, earning All-Big Ten Honorable Mention honors.
Before his time at West Lafayette, O'Brien spent two seasons on staff at Illinois as a defensive analyst. In 2022, the Illini posted an 8-4 record while ranking among the national leaders in 17 defensive categories, including a No. 1 ranking in scoring defense.
O'Brien worked three seasons at Missouri (2018–2020) as a defensive quality control analyst, helping the Tigers to postseason appearances in the Liberty Bowl and Music City Bowl while working primarily with the secondary. His coaching career also includes stops at FIU (2017), Arizona Christian (2015–2016) — where he served as defensive coordinator for two conference championship teams — and Northern Arizona (2013–2014), his alma mater, where he began his career as a graduate assistant coaching the nickels and outside linebackers.
A former defensive back and special teams contributor at Northern Arizona, O'Brien was part of an FCS playoff team in 2012 after transferring from Glendale Community College, where he played quarterback and defensive back and helped lead the Gauchos to back-to-back Valley of the Sun Bowl wins.
O'Brien earned his bachelor's degree in secondary education history from Northern Arizona in 2013 and added a master's degree in educational leadership in 2015.
O'Brien arrived in Evanston following two seasons as the safeties coach at Purdue, where he made an immediate impact on the Boilermakers' defense. In 2023, he was named Our Coaching Network's National Safeties Coach of the Year after mentoring standout freshman Dillon Thieneman to a record-breaking campaign. Under O'Brien's guidance, Thieneman became an AP Third-Team All-American, FWAA Defensive Freshman of the Year, and Big Ten Freshman of the Year, leading all FBS first-years in solo tackles and interceptions. Sanoussi Kane also thrived under O'Brien's direction, earning All-Big Ten Honorable Mention honors.
Before his time at West Lafayette, O'Brien spent two seasons on staff at Illinois as a defensive analyst. In 2022, the Illini posted an 8-4 record while ranking among the national leaders in 17 defensive categories, including a No. 1 ranking in scoring defense.
O'Brien worked three seasons at Missouri (2018–2020) as a defensive quality control analyst, helping the Tigers to postseason appearances in the Liberty Bowl and Music City Bowl while working primarily with the secondary. His coaching career also includes stops at FIU (2017), Arizona Christian (2015–2016) — where he served as defensive coordinator for two conference championship teams — and Northern Arizona (2013–2014), his alma mater, where he began his career as a graduate assistant coaching the nickels and outside linebackers.
A former defensive back and special teams contributor at Northern Arizona, O'Brien was part of an FCS playoff team in 2012 after transferring from Glendale Community College, where he played quarterback and defensive back and helped lead the Gauchos to back-to-back Valley of the Sun Bowl wins.
O'Brien earned his bachelor's degree in secondary education history from Northern Arizona in 2013 and added a master's degree in educational leadership in 2015.
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