Dionesium was a chemical compound that was borne from the blood of the Hyper-Adapter. Designed to turn its users either immortal or relatively immortal, Dionesium was a dangerous chemical, usually turning its users into madmen. It was also the main compound that made up the Lazarus Pits, although contact with the Well of Sins had slightly corrupted it. Those who gained immortality through Dionesium were referred to as Barbatos', a reference to the Hyper-Adapter. The chemical gained its name from the God Dionysus.
- Vandal Savage - The very first Barbatos and the man who spread the legend.
- Ra's al Ghul - The Demon that used the corrupted Dionesium from the pit.
- Simon Hurt - Had his aging slowed by a diluted concentration of Dionesium.
- Talons - Were able to use dionesium within the Electrum Compound.
The Joker: Used dionesium to revive himself throughout history.