Essential oils obtained from Origanum species are characterized by high diversity in composition. In this work, thin-layer chromatography (TLC)—fingerprinting of Origanum species was performed for the first time and enabled the discrimination of three chemotypes (carvacrol, caryophyllene oxide, and terpineol/sabinyl). Gas chromatography—mass spectrometry and statistical analyses confirmed the presence of the mentioned chemotypes and deepened the characterization of the studied essential oils. TLC—bioautography showed that thymol and carvacrol are the main antioxidant compounds in Origanum sp. essential oils (EOs).