A number of splinter organisations functioned over the years either within or in parallel with Hydra, one of the most famous being A.I.M. which began as its research division.
Hydra's main recurring enemies were S.H.I.E.L.D. agents and their leader, Nick Fury.
UniformEditwhile Hydra's operative used a number of costumes and civilian attires, the basic soldiers wore a uniform which has changed little over the decades since its creation: a green suit with yellow accent covering the entire body save for the lower face. A yellow "H" or the organisation's emblem is more often then not worked into the design.
To the left is a version of Hydra's uniform typical of the 1960s to the early 1980s.