Colossus Chess is a series of chess-playing computer programs developed by Martin Bryant, commercially available for various home computers in the 1980s.

Uncommon for microcomputer chess programs of the era, Colossus had a full implementation of the rules of chess, including underpromotion, the fifty-move rule, draw by repetition, and draw by insufficient material. Colossus was also able to execute all the basic checkmates, including the difficult bishop and knight checkmate.

The program was subsequently ported to IBM PC (1990) under the title Colossus Chess X. The new releases featured four chess sets and enhanced graphics developed with the assistance of Gary Thomlinson and Carl Cropley. The opening book was extended to 11,000 positions, and the program had the ability to learn from past playing experiences.