Merga Bien (late 1560s – 1603) was a German woman convicted of witchcraft and perhaps the most famous of the victims in the Fulda witch trials in 1603–05.
She was married three times and was the heiress of her first two husbands, which later played an important part in accusations.
In 1588, she married Blasius Bien and moved from the city, but, fatefully, returned after a conflict with her husband's employers.
At the time, prince abbot Balthasar von Dernbach, who had returned to power in 1602 after a long exile, ordered an investigation of witchcraft in the city.
Her pregnancy was considered an aggravating circumstance; she and her husband had no children although they had been married for fourteen years.