Three-check chess, also simply known as three-check, is a chess variant where a player can win by placing their opponent in check three times. Apart from this, standard rules of chess apply, including starting position and other ending conditions, such as stalemate and checkmate. A move is considered to give one check if the king is threatened, regardless if multiple pieces are checking the king. Three-check can be played over the board, but it is also popular on internet chess servers such as Chess.com and Lichess.

It is unknown specifically where three-check chess originated, but David Pritchard, author of The Encyclopedia of Chess Variants, suspected Soviet origin, and noted that Anatoly Karpov was an "invincible" player of three-check chess in his youth. On Lichess, the three-check world championship is hosted yearly. Other strong players who have played three-check include grandmasters Maxime Vachier-Lagrave and Sergei Zhigalko.

Given that the game is quickly completed, and often not decided by checkmate, three-check players will frequently sacrifice pieces if they are guaranteed to achieve one or multiple checks on the king. Opening diagonals towards the king is inadvisable – 1. d4? allows the immediate 1... e5! taking advantage of white's dark-squared weaknesses upon the a5-e1 diagonal.

International Master Daniel Rensch has written for Chess.com on strategic and tactical opportunities to be wary of while playing three-check: