Enforcer is a role in ice hockey. The term is sometimes used synonymously with "fighter", "tough guy", or "goon". An enforcer's job is to deter and respond to dirty or violent play by the opposition. When such play occurs, the enforcer is expected to respond aggressively, by fighting or checking the offender. Enforcers are expected to react particularly harshly to violence against star players or goalies.

Enforcers are different from pests, players who seek to agitate opponents and distract them from the game, without necessarily fighting them. The pest's primary role is to draw penalties from opposing players, thus "getting them off their game", while not actually intending to fight the opposition player (although exceptions to this do occur). Pests and enforcers often play together on the same line, usually the fourth line. Another related role is the grinder, known for hard work and checking rather than scoring, but not necessarily for fighting.

Enforcers can play either forward or defense, although they are most frequently used as wingers on the fourth forward checking line. Prized for their aggression, size, checking ability, and fists, enforcers are typically less gifted at skill areas of the game than their teammates. Enforcers are typically among the lowest scoring players on the team and receive a smaller share of ice time. They are also not highly paid compared to other players, and tend to move from team to team.

Enforcers are nevertheless often popular on their teams. John Branch wrote in The New York Times: "The enforcer, sometimes mocked as a goon or euphemized as a tough guy, may be hockey's favorite archetype. Enforcers are seen as working-class superheroes—understated types with an alter ego willing to do the sport's most dangerous work to protect others. And they are underdogs, men who otherwise might have no business in the game."

John Scott's reputation as an enforcer and fan favorite helped him earn enough fan votes to secure a spot in the 61st National Hockey League All-Star Game, despite having been demoted out of the league at the time of his election. He unexpectedly played a key role in his division's victory by scoring two goals, where fan response also led to him being named the most valuable player of the tournament. Fighting skills can allow insufficiently talented or smaller players to play in leagues where their hockey skills alone would not have otherwise granted them admission.

Enforcers sometimes take boxing lessons to improve their fighting. Some players combine aspects of the enforcer role with strong play in other areas of the game. Tiger Williams, Bob Probert, Chris Simon, and Tom Wilson are examples of enforcers who showed an occasional scoring flair, with Williams and Probert playing in the midseason All-Star Game. Terry O'Reilly once scored 90 points in a season, being the first player to finish in the top ten regular season scorers while amassing at least 200 penalty minutes, and later became captain of the Boston Bruins.

Sometimes enforcers can do their job by virtue of their reputation. Clark Gillies was among the best fighters in the NHL during his prime, but over time he rarely had to fight because opponents respected and feared him enough that they would not go after his teammates. Some skilled players, such as NHL legend Gordie Howe and NHL all-star Jarome Iginla, were also capable fighters, each functioning effectively as his own enforcer. A "Gordie Howe hat trick" is a player scoring a goal, assisting on a goal, and being involved in a fight during a single game.

In the 1970s, the Boston Bruins and Philadelphia Flyers were known respectively as the "Big Bad Bruins" and "Broad Street Bullies", for stocking up on grinders and enforcers.