There are many versions about the island’s name. According to one myth, it was named after the nymph Syme with whom Poseidon coupled and gave birth to Xthonius, the leader of the first residents of the island. Another imputed the name to Syme the daughter of King Ialissus, who was taken by Glaukos and brought to that place. Glaukos is considered to be the first inhabitant of the island and formidable shipbuilder. One of the ancient names of the island is Aigli and is imputed to the nymph that gave birth to the three Charites. Other known names are Kariki, Metapontida, Elkousa.
According to Homer Nireus, the king of Symi participated in the Trojan War with his three ships.
The first residents of the islands are considered to be the Ikarians, Pelasgians, Achaeans. During 11th century appear Dorians that establish their dominion in the island. Later Symi became a member of the Athenian League.
At Hellenistic Era, Symi was a great naval force. In 1204 the island, along with its surrounding islands, was incorporated to Byzantine Empire.
From 1209 to 1522 appertained to The Knights of Saint John.
In 1522 was conquered by the Turks but had special privileges and regional government because of its developed naval force and commerce.
Participated vividly in the Greek War of Independence in 1821 and raised the flag of the revolution with the people of Hydra. The London Protocol of 1830 handed over Dodecanese to the Turks who revoked most of their privileges.
In 1912 Italians conquered the island
On October 11, 1944 Italians executed the abbot of Panormitis monastery, Chrysanthos Maroulakis with its affiliates.
On September 24, 1944 the Germans destroyed the church of Megali Panagia inside the castle.
On March 3, 1948 Dodecanese became a part of the Greek state.