Demetrius the Fair in the context of "Hellenistic era"

Berenice II Euergetis (267 or 266 – 221 BCE; Greek: Βερενίκη Ευεργέτις, Berenikē Euergetis, "Berenice the Benefactress") was queen regnant of Cyrenaica from 258 to 246 BCE and queen of Ptolemaic Egypt from 246 to 222 BCE as the wife of Ptolemy III. She is sometimes considered co-regent of her Ptolemaic husband.

She married Demetrius the Fair, thus giving him the throne of Cyrenaica, on the death of her father Magas in 250/249 BCE. After a short power struggle with her mother, Berenice married her half-cousin Ptolemy III, the third ruler of the Ptolemaic kingdom. This marriage led to the re-incorporation of Cyrenaica into the Ptolemaic empire. As queen of Egypt, Berenice participated actively in government, was incorporated into the Ptolemaic state cult alongside her husband and worshipped as a goddess in her own right. She is best known for sacrificing her hair as a votive offering, which led to the constellation Coma Berenices being named after her. Berenice was murdered by the regent Sosibius shortly after the accession of her son Ptolemy IV Philopator in 221 BCE.