When a club side wins the domestic double (the league and the cup) and the main continental trophy (e.g. the Champions League) in the same season.
- Example: Bayern Munich capped a wonderful 2012-13 season by completing the treble when they won the German Cup against Stuttgart. They won the Bundesliga title by over 20 points and beat Dortmund in the Champions League final 2-1.
- Example: Seven European sides have completed the treble: Celtic (1967); Ajax (1972); PSV Eindhoven (1988); Manchester United (1999); Barcelona (2009); Inter Milan (2010) and Bayern Munich (2013).