Matthias Sammer (German pronunciation: [maˈtiːas ˈzamɐ]; born 5 September 1967) is a German football official and former player and coach. He played as a defensive midfielder and later in his career as a sweeper.

With Borussia Dortmund as a player, Sammer won the Bundesliga and DFB-Supercup in 1995, the Bundesliga, DFB-Supercup, and European Footballer of the Year in 1996, and the UEFA Champions League and Intercontinental Cup in 1997. Germany won the UEFA Euro 1996 with Sammer as a player, where he was named the tournament's best player, and was subsequently awarded the Ballon d'Or later that year. Sammer retired with 74 total caps, 23 for East Germany and 51 for the unified side. Known for his exceptional defensive skills, including his ability to read the game, make interceptions, and tackle effectively, Sammer is regarded as one of the greatest defenders of all time.

With Sammer as a manager, Borussia Dortmund won the Bundesliga in 2002.

Sammer started his career at Dynamo Dresden when he joined the club's youth team as a nine-year-old in 1976. He made his debut for the senior team under the management of his father, Klaus Sammer, in the 1985–86 season. Playing as a striker, he scored eight goals in his first season as Dynamo finished fifth in the DDR-Oberliga. After being moved to the left wing the following season by new manager Eduard Geyer, he eventually found his place in central midfield during the 1987–88 season.

In the 1988–89 season, Sammer was part of the Dynamo Dresden team which won the East German championship. The same season the club also reached the semi-final of the UEFA Cup where they were knocked out by West German club VfB Stuttgart. The following year Dynamo won the league and cup double, defending the DDR-Oberliga title and also winning the 1990 FDGB-Pokal.

Sammer was formally an officer of the Volkspolizei, as a player of Dynamo Dresden. He enrolled into the Felix Dzerzhinsky Guards Regiment as a 19-year-old. Many players of Dynamo Dresden were assigned to the regiment for their military service. Sammer then served as a non-commissioned officer in the Guards Regiment for three years from 1987, holding the rank of sergeant in the Stasi. The President of SV Dynamo was the head of the Stasi Erich Mielke. Sammer has explained that he would not have been able to continue to play football for Dynamo Dresden if he had refused to serve with the Guards Regiment and that he never saw any weapon or took part in any military exercise. He has described his employment with the Guard Regiment as an alibi to play football to Dynamo Dresden.

In the summer of 1990, Sammer joined VfB Stuttgart of the Bundesliga. Sammer scored 11 times in his debut season as Stuttgart finished sixth in the Bundesliga. The following year Sammer scored nine goals, helping Stuttgart to become the first champions of the reunified Germany.

After two seasons at Stuttgart, Sammer joined Italian club Inter Milan for the 1992–93 Serie A season. Though he was a success on the pitch, scoring four times in 11 appearances, including a goal against Juventus in the Derby d'Italia, Sammer failed to adapt to the Italian lifestyle and returned to Germany in January 1993.