The First XI (or, less commonly, First 11) are the eleven primary players in an organisation's leading team, particularly a football or cricket team. A player who is considered a core part of the starting line-up in a First XI team is often the most proficient in their particular position.

The name is a reference to the fact that they are the first eleven players selected to play for the team—many sports state that clubs must have squads of no fewer than ${\displaystyle x}$ number of players, and this number is often higher than 11. For example, in the Premier League, each club has to designate a squad of 25.