Cylaces

Cylaces or Glak (, misspelled in the manuscripts of Faustus of Byzantium's history) was a 4th-century Armenian eunuch who occupied the office of  (grand chamberlain). He initially defected to the Sasanian side during Shapur II's invasion of Armenia, but later rejoined the Armenians in 368 and fought Shapur II's forces. In 370, he sent messengers to Shapur II, promising him to betray the Armenian king Pap ((r. 370 – 374)). However, this ploy was discovered by Pap, who had Cylaces assassinated.

In Faustus of Byzantium's History of Armenia, Cylaces is split into two characters, both of whom are executed on Pap's orders: an unnamed who is executed for insulting Pap's mother Parandzem, and another one named Glak who is executed for conspiring with the Persians.