The Terminator 3: Rise of the Machines actor has not been seen by his spouse since Wednesday, May 9, and a missing persons report has been filed with police, reports TMZ.
Sources claim that the 32-year-old has been visiting the Skid Row area of Downtown Los Angeles in recent months, and has sparked concerns that he may have got involved with drugs.
Stahl's wife reportedly filed court papers in February over her concerns about his drug use.
The actor's representative has declined to comment on the disappearance reports.
He spent a night in jail back in January after he failed to pay a cab driver his fare in Hollywood.
In January 2011, Stahl joined the Fox pilot Locke & Key. However, the network ultimately passed on the pilot.
Nick Stahl has also starred in Sin City, In the Bedroom and The Man Without a Face.