Salamis (/ˈsæləmɪs/ SAL-ə-miss; Ancient Greek and Katharevousa: Σαλαμίς, romanized: Salamís) or Salamina (Modern Greek: Σαλαμίνα, romanized: Salamína) is the largest Greek island in the Saronic Gulf, about two kilometres (one nautical mile) from the coast of Athens' port of Piraeus and about 16 km (8+1⁄2 nmi) west of Athens center.

The chief city, Salamina, lies in the west-facing core of the crescent on Salamis Bay, which opens into the Saronic Gulf. On the eastern side of the island its main port, Paloukia, connects the island with Perama in the western part of Athens urban area through a frequent ferry line and is the second largest port in Greece in terms of passengers, after the port of Piraeus.

The traditional etymology of Salamis derives it from the eponymous nymph Salamis, the mother of Cychreus, the legendary first king of the island. A more modern theory considers "Salamis" to come from the root sal 'salt' and -amis 'middle'; thus Salamis would be the place amid salt water. A theory presented by Martin Bernal in his book Black Athena, which has been overwhelmingly rejected by orientalists, classicists and archaeologists, has attempted to connect the name to the Semitic root Š-L-M 'health, safety, peace', because of the well-sheltered harbor.

From at least the 13th century until the 19th century, the town, the island, and the bay of Salamis were called Koulouri (Κούλουρη), because of its round shape (κόλουρο). The ancient name was revived in the 19th century. The name Koulouri is still used informally for the town. The island is known in Arvanitika as Κȣλλȣρι ("Kulluri").

Salamis was probably first colonised by Aegina and later occupied by Megara, but became an Athenian possession in the time of Solon or Peisistratos, following the war between Athens and Megara around 600 BC. According to Strabo, the ancient capital was at the south of the island; in classical times it was to the east, on the Kamatero Peninsula overlooking the Strait of Salamis; in modern times it is on the west.

According to Homer's Iliad, Salamis took part in the Trojan War with twelve ships under the leadership of Ajax (Aias)

Salamis island is known for the Battle of Salamis, the decisive naval victory of the Athenian-led allied Greek fleet, led by Themistocles, over the Persian Empire in 480 BC. It is said to be the birthplace of Ajax and Euripides, the latter's birth being popularly placed on the day of the battle. In modern times, it is home to Salamis Naval Base, headquarters for the Hellenic Navy.

Arvanites were recorded among the inhabitants of the island in 1688. They lived in poverty as most of the Arvanites in Greece at the time.