The Hellenic Navy (HN; Greek: Πολεμικό Ναυτικό, romanized: Polemikó Naftikó, lit. 'War Navy', abbreviated ΠΝ) is the naval force of Greece, part of the Hellenic Armed Forces. The modern Greek navy historically hails from the naval forces of various Aegean Islands, which fought in the Greek War of Independence. The Hellenic Navy formed during the Hellenic Period ruled by monarchy (1833–1924 and 1936–1973) that has been recognized as the Royal Hellenic Navy (Βασιλικόν Ναυτικόν, Vasilikón Naftikón, abbreviated ΒΝ).

The Hellenic Navy is a Green-water navy. The total displacement of the fleet is approximately 150,000 tons. The HN also operates a number of naval aviation units.^{[citation needed]}

The motto of the Hellenic Navy is "Μέγα τὸ τῆς θαλάσσης κράτος" from Thucydides' account of Pericles' oration on the eve of the Peloponnesian War. This has been translated as "The rule of the sea is a great matter". The Hellenic Navy's emblem consists of an anchor in front of a crossed Christian cross and trident, with the cross symbolizing Greek Orthodoxy, and the trident symbolizing Poseidon, the god of the sea in Greek mythology. Pericles' words are written across the top of the emblem.

"The Navy, as it represents a necessary weapon for Greece, should only be created for war and aim to victory."

— Greek Government (1866)

The history of the Hellenic Navy begins with the birth of modern Greece, and due to the maritime nature of the country, it has always featured prominently in modern Greece's military history.

At the beginning of the Greek War of Independence, the naval forces of the Greeks consisted primarily of the merchant fleet of the Saronic islanders from Hydra, Spetsai and Poros and also the islanders of Psara and Samos. The fleet was of crucial importance to the success of the revolution. Its goal was to prevent as much as possible the Ottoman Navy from resupplying the isolated Ottoman garrisons and land reinforcements from the Ottoman Empire's Asian provinces.

Although Greek crews were experienced seamen, the light Greek ships, mostly armed merchantmen, were unable to stand up to the large Ottoman ships of the line in direct combat. So the Greeks conducted the equivalent of modern-day naval special operations, resorting to the use of fireships (Greek: πυρπολικά or μπουρλότα), with great success. It was in the use of such ships that courageous seamen like Konstantinos Kanaris won international renown. Under the leadership of capable admirals, most prominently Andreas Miaoulis from Hydra, the Greek fleet achieved early victories, guaranteeing the survival of the revolution in the mainland.