Filiki Eteria or Society of Friends (Greek: or ) was a secret organization founded in 1814 in Odessa, whose purpose was to overthrow the Ottoman rule of Greece and establish an independent Greek state. Society members were mainly young Phanariot Greeks from Constantinople and the Russian Empire, local political and military leaders from the Greek mainland and islands, as well as several Orthodox Christian leaders from other nations that were under Hellenic influence, such as Karaore from Serbia, Tudor Vladimirescu from Romania, and Arvanite military commanders. One of its leaders was the prominent Phanariote Prince Alexander Ypsilantis. The Society initiated the Greek War of Independence in the spring of 1821.

Alexandros Ypsilantis (Greek: Αλέξανδρος Υψηλάντης, romanized: Aléxandros Ypsilántis, pronounced [aˈleksanðros ipsiˈla(n)dis]; Romanian: Alexandru Ipsilanti; Russian: Александр Константинович Ипсиланти, romanized: Aleksandr Konstantinovich Ipsilanti; 12 December 1792 – 31 January 1828) was a Greek nationalist politician who was member of a prominent Phanariot Greek family, a prince of the Danubian Principalities, a senior officer of the Imperial Russian cavalry during the Napoleonic Wars, and a leader of the Filiki Etaireia, a secret organization that coordinated the beginning of the Greek War of Independence against the Ottoman Empire.