The Book of Lairs is an accessory book for the Dungeons & Dragons fantasy role-playing game, first published by TSR in 1986. It contains an assortment of monster-themed mini-adventures. A second volume was published in 1987. TSR coded the accessories REF3 and REF4 respectively, as part of a series of similarly-coded accessories. Both volumes were received well by critics, with the second being seen more positively than the first.