Hagop Vartovyan (Armenian: ????? ?????????), better known as Güllü Agop (Armenian: ???????? ?????), (took later the name Yakub), (1840 in Constantinople – 1902 in Constantinople) was an Ottoman Armenian theatre director as well as an occasional actor.
He is widely credited with having laid the bases for Turkey's modern and nationally renowned performing arts institution that became the Istanbul City Theatres (Turkish: Istanbul Sehir Tiyatrolari).
In his qualities of organizer, sponsor and figure of support for writers and spectators, Güllü Agop is one of the 19th century pioneers of the Turkish Theatre art as a whole.
He was accepted as the founder of the modern Turkish Theatre.