Jim O'Neil (born October 26, 1978) is an American football coach who currently is the defensive assistant for the Detroit Lions.
Previously he was the defensive coordinator at Northwestern University and as assistant coach in the NFL for the New York Jets, Buffalo Bills, Cleveland Browns, the San Francisco 49ers and Las Vegas Raiders.
He was moved to assistant defensive backs coach in 2010 and remained in that position through the 2012 season.
After the 2013 season, O'Neil was hired as the defensive coordinator of the Cleveland Browns in 2014, but was relieved of his duties after the 2015 season due to a coaching overhaul after head coach Mike Pettine was fired.
O'Neil was hired by Chip Kelly on January 26, 2016 to become the defensive coordinator of the San Francisco 49ers.