Genesius (Greek: Γενέσιος, Genesios; Armenian: Հովսեփ Գենեսիուս) is the conventional name given to the anonymous Byzantine author of Armenian origin of the tenth century chronicle, On the reign of the emperors.
Traditionally, he has been regarded as the son or grandson of Constantine Maniakes.
Composed at the court of Constantine VII, the chronicle opens in 814, covers the Second Iconoclast period and ends in 886.
It presents the events largely from the view of the Macedonian dynasty, though with a skew less marked than the authors of Theophanes Continuatus, a collection of mostly anonymous chronicles meant to continue the work of Theophanes the Confessor.
The chronicle describes the reigns of the four emperors from Leo V down to Michael III in detail; and more briefly that of Basil I.