The Keep on the Borderlands is a Dungeons & Dragons module by Gary Gygax, first printed in December 1979. In it, player characters are based at a keep and investigate a nearby series of caves that are filled with a variety of monsters. Designed to be used with the Dungeons & Dragons Basic Set, it was included in the 1979–1982 editions of the Basic Set. It was designed for people new to Dungeons & Dragons.