Skat (German pronunciation: [ˈskaːt]), historically Scat, is a three-player trick-taking card game of the ace–ten family, devised around 1810 in Altenburg in the Duchy of Saxe-Gotha-Altenburg. It is the national game of Germany and, along with Doppelkopf, it is the most popular card game in Germany and Silesia and one of the most popular in the rest of Poland. A variant of 19th-century Skat was once popular in the US. John McLeod considers it one of the best and most interesting card games for three players, and Kelbet described it as "the king of German card games." The German Skat Association assesses that it is played by around 25 million Germans – more than play football.

Skat was developed by the members of a local Tarock club, the Brommesche Tarok-Gesellschaft around 1810–1813 in Altenburg, in what is now the State of Thuringia, Germany.

Skat is based on the three-player Tarot game of Grosstarock and the four-player game of Schafkopf (forerunner of American Sheepshead). It has become the most loved and widely played German card game, especially in German-speaking regions. In the earliest known form of the game, the player in the first seat was dealt twelve cards and the other two players ten each. He then made two discards, constituting the Skat, and announced a contract. But the main innovation of this new game was that of the bidding process.

The earliest recorded rules for "Scat" date to 1835, by when it was already popular in the Kingdom of Saxony, especially in the Duchy of Altenburg and the surrounding area. These describe a game for 3 players with German-suited cards who received 10 each in packets of 3, 2, 3 and 2, the two remaining cards being dealt to the table as a talon known as the Scat. There were just two contracts – Frage and Solo – and forehand opened the bidding or passed. A Frage bidder could be overcalled by a Solo and either could be overcalled by the same contract in a higher-ranking suit, the suits ranking in the same order as in the modern game. The declarer needed 61 card points to win and there were bonuses for scoring 90 (Schneider), taking all tricks (Schwarz) and, optionally, for holding or lacking matadors in unbroken sequence from the top. The four Unters were permanent trumps ranking above the trump suit.

The first book on the rules of Skat, Das Scatspiel: Nebst zwei Liedern, was published in 1848 by one of its inventors, secondary school teacher J. F. L. Hempel. Nevertheless, the rules continued to differ from one region to another until the first attempt to set them in order was made by a congress of Skat players on 7 August 1886 in Altenburg. These were the first official rules finally published in a book form in 1888 by Theodor Thomas of Leipzig. The current rules, followed by both the International Skat Players Association, German Skat Federation and British Skat Association, date from Jan. 1, 1999.

The word Skat is a Tarock term derived from the Latin word scarto, scartare, which means to discard or reject, and its derivative scatola, a box or a place for safe-keeping. The word scarto is still used in some other Italian card games to this day. Skat is completely unrelated to an American game called Scat.

Skat is particularly popular in Germany. Tournament Skat is regularly held in restaurants. In contrast to most other card games, Skat is organized as a sport, with Skat associations, clubs, ranking lists and even a national league. Most German Skat clubs are affiliated to the German Skat Association (DSkV), which organizes the championships. In addition, the global organisation, the International Skat Players Association, is primarily responsible for organising the World and European Championships, but its subdivision, ISPA Germany, like the DSkV, organizes its own German individual and team championship and leagues, among other activities.

Skat is played on a lesser scale in countries bordering Germany, including the Netherlands, Denmark (especially southern Jutland), Poland and Austria.