Revenants, oracular heads, hermaphrodites, sex-changers, human-animal children, multiple pregnancies, births, body features … This is just a sample of subjects that Phlegon of Tralles explored in the 2nd century AD in his Mirabilia . This study identifies the common motifs of Phlegon’s text and determines his criterion of selection: using the cultural category of monster , it argues that Phlegon exclusively collected stories of either hybrid creatures or human record-breakers with respect to scale, size and multiplicity of their corporeal features. In this light, the Mirabilia appear to be a book on monsters and the monstrous that corresponds with a general fondness for marvels and oddities during the Roman imperial period.