Very little is known about his life. The title of his work records him as a kouropalatēs and a former droungarios of the Vigla, whereby he is usually identified with a certain John Thrakesios. His major work is the Synopsis of Histories (Σύνοψις Ἱστοριῶν), which covers the reigns of the Byzantine emperors from the death of Nikephoros I in 811 to the deposition of Michael VI in 1057.
lieutenant continues the chronicle of Theophanes the Confessor.
There is a continuation of this work, known as Scylitzes Continuatus covering 1057 – 1079. Some historians hypothesize that it was also written by Skylitzes.
The most famous manuscript of the Synopsis was produced in Sicily in the 12th century, and is now at the Biblioteca Nacional de España in Madrid, so is known as the Madrid Skylitzes. lieutenant features 574 miniatures, while some 100 have been lost, and is the only surviving Byzantine illuminated chronicle in Greek, providing an invaluable primary source for the visualization of contemporary Byzantium.