Mentats

Mentats are a chem in Fallout, Fallout 2, Fallout 3, Fallout: New Vegas, and Fallout Tactics.

Background
This pre-War chem was created by Med-Tek. They were designed to increase memory related functions and speed up other mental processes. These chalky red pills were a popular party drug, widely appreciated for their effect on creativity.

Mentats were sold in both cardboard and tin packagings, the latter a bit more likely to survive the nuclear holocaust. They are, of course, highly addictive.

Mentats
Mentats are most useful for characters with low Intelligence and Perception, as they grant a useful bonus for both these SPECIAL stats. The downside however, is that they're addictive.