Helena Kantakouzene, Empress of Trebizond
Helena Kantakouzene (died 1463) was the second wife of David of Trebizond, the last Emperor of Trebizond.
Recent research has led to doubts regarding her existence.
Irene of Trebizond
Irene of Trebizond( died around 1382) was the bigamous wife of Basil of Trebizond, by whom he had two sons, Alexios and John( later Alexios III of Trebizond), and possibly three daughters Anna, Maria and Theodora.
Rusudan of Georgia, Empress of Trebizond
Rusudan of Georgia, Empress of Trebizond was a consort of Manuel I of Trebizond, and the mother of Empress Theodora.
Very little is known for certain about her.
Anna of Trebizond
Anna Anachoutlou( died 1342) was Empress of Trebizond from July 17, 1341, to September 4, 1342.
Anna was the elder daughter of Emperor Alexios II of Trebizond and his Georgian wife, Djiadjak Jaqeli.
David of Trebizond
David Megas Komnenos (– 1 November 1463) was the last Emperor of Trebizond from 1459 to 1461.
He was the third son of Emperor Alexios IV of Trebizond and Theodora Kantakouzene.
Following the fall of Trebizond to the Ottoman Empire, he was taken captive with his family to the Ottoman capital, Constantinople, where he and his sons and nephew were executed in 1463.
In July 2013, David and his sons and nephew were canonized by the Holy Synod of the Patriarchate of Constantinople.
Their feast day was determined as 1 November, the anniversary of their deaths.
Pankratios of Trebizond
Pankratios or Pangratios was the first Metropolitan bishop of Trebizond following the Ottoman conquest of the Empire of Trebizond in 1461.
Nothing is known about Pankratios' origin or early career prior to his appointment as metropolitan.
The see had been vacant since the capture of Trebizond and the incorporation of the Empire of Trebizond to the Ottoman Empire in 1461, as the bulk of the Trapezuntine upper classes, including the secular nobility and the ecclesiastical hierarchy, were transferred to the Ottoman capital, Constantinople.
It was not until ca. 1472 that the vacancy was addressed.
This was partly the result of the appointment of the Trapezuntine Symeon I as Patriarch of Constantinople, but owed more to political considerations on the part of the Ottoman Sultan, Mehmed II: the Christians of the Pontus region around Trebizond had been restive against Ottoman rule, and were encouraged by the neighbouring Aq Qoyunlu sultan Uzun Hassan.
The latter was linked through family ties with the former imperial house of Trebizond, and lent his support to a scion of that house, Alexios Komnenos.
In order to counteract the threat of a rebellion, the Sultan elevated Symeon to the patriarchal throne, and he immediately appointed Pankratios to the metropolitan throne of Trebizond.
It appears, however, that the latter was unable to satisfy the Sultan's expectations about calming the province, and already after a few months Mehmed II demanded his replacement.
Pankratios was succeeded by Dorotheos II, and nothing further is known of him thereafter.
Theodora of Trebizond
Theodora Megale Komnene,( before 1253 – after 1285), was Empress of Trebizond from 1284 to 1285.
All Michael Panaretos tells us about her is that she was a daughter of Emperor Manuel I of Trebizond by Rusudan, a Georgian princess.
Although some consider her Manuel's second wife, Michel Kuršanskis has argued that Rusudan may have been simply his mistress.
Kuršanskis also notes that the evidence is insufficient to determine if Theodora was identical with one of the princesses of Trebizond mentioned in the Chronicle of Bishop Stephanos who married a noble or the king of Georgia, or if she had been a nun — much as Anna Anachoutlou was before her usurpation in the following century.
In 1284, with the help of Georgian King of Imereti, David VI Narin she managed to seize the crown from her half- brother, Emperor John II.
John II may have taken refuge in Tripolis.
Shortly afterwards she was defeated and John regained his throne, but she had managed to reign long enough to have minted her own coins.
A few types of silver aspers and bronze nomismas are evidence that she was the only Empress of Trebizond to have coined money.
Her fate after John's restoration is unknown.
Helena Kantakouzene
Helena Kantakouzene (1333 – 10 December 1396) was the Empress consort of John V Palaiologos in the Byzantine Empire.
Maria of Gothia
Maria of Gothia was the first wife of David of Trebizond, last Emperor of Trebizond, whom she married in 1426.
Irene Palaiologina of Trebizond
Irene Palaiologina
( Greek: Ειρήνη Παλαιολογίνα," Eirēnē Palaiologina"),( c. 1315 – after 1341) was Empress of Trebizond from April 6, 1340 to July 17, 1341.
She was an illegitimate daughter of the Byzantine Emperor Andronikos III Palaiologos, and she married Emperor Basil of Trebizond in 1335.

Question: Where did Helena Kantakouzene, Empress Of Trebizond's husband die?
Answer: Constantinople