Hard Knocks is a reality sports documentary television series produced by NFL Films for HBO.

First broadcast in 2001, the show typically follows a National Football League (NFL) team through its training camp and covers the team's preparation for the upcoming football season. Beginning in 2021, the show has also dedicated an additional season of television to following an additional team throughout the NFL regular season, followed by an additional season to follow another team through the NFL offseason starting in 2024.

The series depicts the personal and professional lives of players, coaches, and staff, including their family life, position battles, and even inside jokes and pranks. It particularly focuses on rookies' adjustments to playing in the NFL, usually with emphasis on the team's most recent top draft pick. It usually also chooses to focus on undrafted and journeyman players who are attempting to make the team.

The NFL and HBO have called Hard Knocks "the first sports-based reality series" in television history. The 20th season featured the New York Jets in their second appearance on the show, as well as the Miami Dolphins. In 2024, the series expanded to cover a team in the off-season (New York Giants), during training camp (Chicago Bears), and will feature an entire division during the regular season (AFC North).