Mountain bikes designed to use a rigid fork. This includes two types of designs, each having their own advantages:
Suspension-corrected bikes are designed to work with a special "suspension-corrected" rigid fork. This rigid fork is roughly the same length as an equivalent suspension fork so either may be swapped without significantly affecting the bike's geometry. This is advantageous for riders who want to use a suspension fork on the trail and a rigid fork for bikepacking (or upgrade from rigid to suspension at a later date).
Non-suspension-corrected bikes are designed exclusively for use with a rigid fork. These designs are popular for bikepacking since they can be designed with a larger frame triangle and thus can carry more cargo via a frame bag. The fork, meanwhile, can be made lighter since there is less leverage on it due to the shorter length.