In the NFL, there is no definitive answer to who the strongest player is. However, there are a few players who consistently dominate their opponents and can be considered among the strongest in the league.
One of these players is JJ Watt of the Houston Texans. He is a 6'5, 290-pound defensive end who has been terrorizing quarterbacks since he entered the league in 2011. In just four seasons, he has already racked up 50 sacks and has been named Defensive Player of the Year twice. His strength, size and speed make him nearly impossible to block, and he shows no signs of slowing down anytime soon.
Another player who could be considered the strongest in the NFL right now is Adrian Peterson of the Minnesota Vikings. He is a 6'1, 220-pound running back who has been one of the most dominant forces in football since he was drafted in 2007. In his seven seasons in the league, Peterson has rushed for over 10,000 yards and 84 touchdowns while becoming one of only six players to ever eclipse 2,000 rushing yards in a season. His rare combination of size, speed and power makes him virtually unstoppable on the field, and he's shown time and time again that he can carry an entire team on his back if need be.
So while there isn't necessarily one strongest player in the NFL right now, there are definitely a few guys who have earned that distinction through their play on the field.