Here you will find all the character that have lead Hydra and have gained the title of Supreme Hydra or Hydra Supreme. Note: This does not include Madame Hydra or the likes.
Prime Universe

Hydra’s founder
Other possible future figures (Prime Universe only); Supreme Hydra | Otto Vermis | Tomi Shishido | American Supreme Hydra | Arnold Brown | Deltite | Edgar Lascombe | Freehold Invader Supreme Hydra | Richard Fisk