0-8-4 may refer to:
- Peruvian 0-8-4 - A weapon developed by a group of HYDRA scientists.
- 0-8-4 - The S.H.I.E.L.D. procedural code describing an item of unknown origin.
- 0-8-4 - The second episode of the first season of Agents of S.H.I.E.L.D.
- Russian 0-8-4 - An object retrieved by Phil Coulson and Melinda May early on in their careers.