No player has never won four Defensive Player of the Year awards in NFL history. Lawrence Taylor won his third in 1986. JJ Watt won his third Defensive Player of the Year award in 2015. In 2020, Aaron Donald won his third Defensive Player of the Year award with the Los Angeles Rams.
The same can be said about the NFL’s Offensive Player of the Year where Earl Campbell and Marshall Faulk are the only players to win the award three times. Only MVP has a player won the award more than three times with Aaron Rodgers and Peyton Manning winning four and five times respectively.