Herman Magnus af Petersens, born 1842 - died 1903) was a Swedish nobleman, Hofjægermester (hunting master) and a landowner.

[1] Af Petersens was the son of Captain Carl Herman af Petersens (1801-1843), member of the Swedish nobility and his wife, Sofia Carolina Dahlqvist (1818-1900).

He was the first hofjægermester and owner of the Erstabik estate in Nacka.

On 4 July 1889 af Petersens sold 890 hectares from the estate.

[2] Herman Magnus was married to Countess Sofia Albertina Charlotta Augusta Eleonora Catharina Stenbock (1843-1916), daughter of Count Magnus Albert Carl Gustaf Arvid Stenbock (1800-1871) and his wife, Countess Johanna Margaretha Hamilton (1809-1892).