Light Transport; Low Wing; 2 Turboprop Eng
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Communication Breakdown
Deviation / Discrepancy - Procedural Hazardous Material Violation; Deviation / Discrepancy - Procedural Published Material / Policy
General Maintenance Action
Human Factors
Onboard the aircraft was a piece of Hazmat which I was unaware of.  The company manifest did not disclose it and I was not notified by any company personnel.  I am unsure of when the piece was loaded; if it was during the preload process or while I was present.  Upon finding the Hazmat during aircraft unloading; I reported it to Dispatch.
Captain reported the transport of undocumented Hazmat package.