The use of third-parties in corrupt international arms deals is ubiquitous. Agents and intermediaries play a role in many of the cases included in the World Peace Foundation’s Compendium of Arms Trade Corruption. Indeed, their near-universal appearance in the compendium entries means that merely highlighting their presence reveals little. It is the variety of roles these actors have played in arms deals that demands greater attention. This paper presents a preliminary typology of arms trade intermediaries as encountered in the more than 40 cases of corruption in the compendium.