Demetrius of Liubar or Liubartas (also Lubart, Lubko, Lubardus, baptized Dmitry; died ~1383) was Prince of Lutsk and Liubar (Volhynia) (1323-1383), Prince of Zhytomyr (1363-1374), Grand Prince of Volhynia (1340-1383), Grand Prince of Galicia and Volhynia (1340-1349).
The origin of Liubartas is uncertain. It is known that he was the youngest son of Gediminas, Grand Duke of Lithuania. In the early 1320s he married a daughter of Andrew of Galicia and ruled Lutsk with Liubar (today town in Zhytomyr Oblast) in eastern Volhynia. After Andrew and his brother Lev II died around 1322, Galicia–Volhynia did not have a male successor. Instead of promoting Liubartas and causing a war with Poland, Gediminas compromised with Władysław I of Poland. Both parties agreed to install Boleslaw-Yuri II, nephew of Leo and Andrew.
Boleslaw-Yuri was a son of Trojden I of Masovia from the Piast dynasty, a cousin of Władysław I, and nephew of Gediminas' son-in-law Wacław of Płock. At the time Boleslaw was fourteen years old and was betrothed to Eufemija, daughter of Gediminas. Liubartas continued to rule Lutsk and Volodymyr-Volynskyi. That way the Galicia–Volhynia Wars were postponed until after Boleslaw's poisoning in 1340. He was poisoned by rebellious nobles, who invited Liubartas to become the ruler for both Galicia and Volhynia. Sources are too scarce to fully reconstruct events between 1341–1349.
Down on your knees you cry for help
Unleashed the rage, no reprieve
What you've done is coming back around
Instant karma, appropriate I believe
Laugh out loud I beat you harder
Both hands broken you can't fight back
For years you tried to break me
Turned round no fists my odds are stacked
Strapped and abused in misery
Chewed up pissed on cast aside
No place for me in your plan for life
Learned through time to depend on you
And you ask me why I'm bitter
Placed you on a pedestal and fell
Outstayed my welcome once again
Your actions unacceptable
And you ask me why I'm bitter
Two's company, three's a crowd
Time for me, disallowed
Beaten fucked up it feels so sweet
Justice served for what you've done
Left now taped up in your defeat
Your time for repent is nigh, scum
And I see you smiling now
And you ask me why I'm bitter
You know I really used to like you don't you?
Consciousness slips away over time