The Hellenic orogen is a composite one, consisting of three orogenic belts: (1) the Cimmerian internal belt, created in pre–late Jurassic times as a result of the collision of northward-drifted Cimmerian continental fragments with Eurasia, (2) the Alpine orogenic belt, created in Cretaceous–Tertiary times after the Neo-Tethyan subduction beneath the Cimmeria-Eurasia plate and the collision of the Apulian microplate with this composite Cimmeria-Eurasia plate, and (3) the Mesogean orogenic belt along the External Hellenic arc, which resulted from the underplating of the Mesogea-Africa plate beneath the Alpine-Cimmeria-Eurasia plate in Miocene–Pliocene times and the exhumation of the Cretan–southern Peloponnesus tectonic windows. Tertiary Alpine collisional tectonics (imbrication and nappe stacking) formed the nappe pile of the Hellenic orogen. A late orogenic extension followed the lithospheric thickening and caused the collapse and crustal thinning with exhumation of the lower crustal units as metamorphic core complexes in Crete, the Southern Peloponnesus, and the Cyclades and a series of tectonic windows in continental Greece (i.e., the windows of Olympus, Ossa, Rizomata, and Krania) consisting of Mesozoic and Tertiary neritic carbonates of the External Hellenides. Five deformation events have been recognized in Greece: (1) the D 0 compressional event in the Eocene (ca. 45 Ma), contemporaneous with the high-pressure–low-temperature (H P -L T ) metamorphism that created the blueschist belt along Olympus, Ossa, Euboea, and the Cyclades; (2) the D 1 extensional event in the late Eocene–early Oligocene, contemporaneous with the greenschist metamorphism in the Hellenic Hinterland (Rhodope and Serbomacedonian zones) and some of the Internal Hellenides zones (Circum Rhodope, Axios-Vardar, and part of the Cyclades); (3) the D 2 compressional event in the late Oligocene–early Miocene, contemporaneous with the 25 Ma H P -L T metamorphism in Crete and the southern Peloponnesus, which produced the imbrication and nappe stacking; (4) the D 3 extensional event in the early–middle Miocene, which produced low-angle shear zones, thinning of the crust, uplift and exhumation of the H P -L T metamorphic rocks as core complexes, and tectonic windows in Crete, the southern Peloponnesus, and the Cyclades; and (5) the D 4 extensional phase, the final deformational event in Pliocene to recent times. The direction of the extension is generally north-south, producing east-west-trending normal faults and locally reactivating previous faults of other trends as strike-slip faults. In northern Greece, the direction of the active extension differs slightly from the general north-south direction in places, particularly in northwestern Macedonia, where it becomes almost northwest-southeast, as is deduced from both focal mechanisms of large and small earthquakes and geological field measurements along active faults.