The Seattle Seahawks are a professional American football team based in Seattle. The Seahawks compete in the National Football League (NFL) as a member club of the league's National Football Conference (NFC) West, which they rejoined in 2002 as part of a conference realignment. The club entered the NFL as an expansion team in 1976 in the NFC. From 1977 to 2001, Seattle was assigned to the American Football Conference (AFC) West. They have played their home games at Lumen Field in Seattle's SoDo neighborhood since 2002, having previously played home games in the Kingdome (1976–1999) and Husky Stadium.

The 12th man or 12th player is a collective term for fans of sports teams in many eleven-a-side games, in particular association football or American football. As most football leagues allow a maximum of eleven players per team on the playing field at a time, referring to a team's fans as the 12th man implies that they have a potentially helpful and significant role in the game.