Roman
Roman (Роман), known as Roman the Great, was king of Ruthenia.
History
Roman was the eldest son of Mstislav II (Мстислав), prince of Volhynia. He was sent to rule over the principality of Novgorod in 1168.
His father died in 1170, leaving Roman to inherit his principality.
Separately, there was also a succession crisis in the principality of Halych (alt. Galicia) following the death of Yaroslav (Ярослав) in 1187. One son, Oleg, was appointed the principality by Casimir II, but he was shortly assassinated. the local nobility favored Roman as prince. Another son, Vladimir II (Володимир), fled to Hungary seeking military support for his claims. Roman took advantage of this crisis and seized Halych for himself. Once the Hungarians arrived however, the city quickly fell. Roman fled back to Volhynia.
Vladimir was imprisoned by the Hungarians and Andrew was propped up in his place. Vladimir escaped in 1190, fled to Poland, and eventually returned with military support to expel Andrew. He died in 1198 without an heir, so the principality of Halych finally passed to Roman. This created the principality of Galicia-Volhynia, the predecessor state to the kingdom of Ruthenia.