Syriza as a unitary party was formed through the merger of the following parties (in alphabetical order in English):[71]
Active Citizens (Ενεργοί Πολίτες): democratic socialism, patriotism
Anticapitalist Political Group (ΑΠΟ): communism, Trotskyism, anti-capitalism
Citizens' Association of Riga (Velestinli): patriotism, internationalism, democracy, ecology, social justice[72]
Coalition of Left, of Movements and Ecology (Synaspismós or SYN): democratic socialism,[73] eco-socialism,[5] eurocommunism,[74] environmentalism,[73] feminism[73]
Communist Organization of Greece (KOE): maoism, communism
Communist Platform of Syriza: Greek section of the International Marxist Tendency, communism, Trotskyism[75]
Democratic Social Movement (DIKKI): left-wing nationalism, socialism,[76] Euroscepticism[77]
Ecosocialists of Greece: eco-socialism, green politics
Internationalist Workers' Left (DEA): revolutionary socialism, communism, Trotskyism
Movement for the United in Action Left (KEDA): communism, Marxism–Leninism
New Fighter: democratic socialism, social democracy
Radical Left Group Roza: Luxemburgism, feminism
Radicals (Ριζοσπάστες): democratic socialism, patriotism
Red (Κόκκινο): communism, Trotskyism
Renewing Communist Ecological Left (AKOA): democratic socialism, Eurocommunism, green politics
Union of the Democratic Centre (EDIK): radicalism, social liberalism, centrism
Unitary Movement: democratic socialism, social democracy
Also a number of independent leftist activists