Head of the God Osiris
Slate, 7 7/8 x 4 3/4 in. (20 x 12 cm)
Late Period, second half of XXVI Dynasty, 595-525 B.C.E.
Brooklyn #48.163, Charles Edwin Wilbour Fund
Photos © Joan Lansberry, May 2008-2016

(From the info card)
"Figures of the god Osiris are particularly common from the Late Period (circa 664332 B.C.). The craftsmanship of this figure is of a very high standard, the head executed virtually without fault. The bland and benign expression of the face is characteristic of work after the beginning of Dynasty XXVI. That the false beard is attached under the chin and does not envelop it suggests a dating in the second half of the dynasty."

Osiris is wearing the White Crown:

"Hedjet is the formal name for the White Crown of pharaonic Upper Egypt."
Illustration from Wikipedia

While at Wiki, I saw a photo of a statue whose head is very similar to the one at the Brooklyn Museum:

Uploaded by a 'Neithsabes', aka 'Sebi', the caption reads:
Statuette en bronze niellé d'or représentant le dieu Osiris - Basse époque - Musée du Louvre
Bronze statuette plated with gold representing the god Osiris - Old Kingdom - Louvre Museum

It is very likely the Brooklyn head went with a similar body.