The penalty box (sometimes called the sin bin,bad box, or simply bin) is the area in ice hockey, rugby league, rugby union and some other sports where a player sits to serve the time of a given penalty, for an offense not severe enough to merit outright expulsion from the contest. Teams are generally not allowed to replace players who have been sent to the penalty box.

Ice hockey has popularized the term "penalty box", and in most cases it is just that—a small isolated bench surrounded by walls on all four sides, with the side facing the ice having the access door. There are typically two penalty boxes: one for each team. In ice hockey a period in the box occurs for all penalties unless circumstances call for an ejection or a penalty shot. If three or more players are serving penalties at once, the team will continue playing with three on the ice but will not be allowed to use the players in the box until their penalties expire.

Most leagues specify that a team cannot replace on the ice a member serving a minor (2-minute) penalty. This results in situations such as the power play, in which the opposing team outnumbers the penalized (shorthanded) team, and (in the event of coincidental minor penalties) situations in which both teams must skate with only five players (including the goaltender) on the ice.