Mercenary is a game aid for Game Designers' Workshop's Traveller role-playing game that generates characters with an Army or Marines background. It follows the rules in Book 4: Mercenary, published in 1978. It includes two starting options for the player character:
Enrollment in the Military or Naval Academy as defined in an article in The Journal of the Travellers' Aid Society, issue 10, published in 1981. Application to flight school for marine characters achieving honors is not supported. A +1 DM on promotion die rolls is available for both army and marine academy graduates.
Enrollment in college as defined in Book 5: High Guard, 2nd edition, published in 1980. Application to medical school or flight school for characters achieving honors is not supported.
At each point in the character generation rules where the player may select options, these are offered, along with a description that includes the success die roll and die modifiers, if any.