E. Gary Gygax wrote the beloved G-series of modules back in the mid to late '70s. The first two installments ran only 8 pages each (the last being a whopping 16) and all came with maps on the inside of the folder-cover. It is easy to refer to them as beloved since, from the moment of their original printing till now it is safe to say that no other module or series has so ingrained itself into the fabric of the fantasy role playing community.
From the Introduction:
This adventure is designed for a party of 5 to 8 characters with levels ranging from 6 to 10. It should contain at least one cleric and magic user and several fighters; dwarf and gnome fighters being the more preferred for their subterranean skills. A party of Prerolled characters is provided in the appendices after the adventure and can be used by the DM to add NPCs to the party or to allow players lacking a character of appropriate level to venture along.