This Special Issue, entitled "Cranial Nerves: phylogeny, ontogeny, morphology and clinical significance," has been divided into two consecutive volumes. We present here the first volume, devoted to phylogeny and ontogeny. Articles in this volume examine these two topics from a microscopic point of view. This volume includes an historical review that serves as an introduction. It also includes a review of the organization of cranial nerves from a neuromeric perspective which, together with two articles in amphioxi and lampreys, give emphasis to a comparative approach. Finally, several articles examine cranial nerves zero (nervus terminalis), I (olfactory), II (optic), III, IV and VI (oculomotor), VIII (cochlear and vestibular), and XI (accessory or spinal). Together, they provide a general overview of the neuroanatomical organization of cranial nerves, while offering insights into an evo-devo paradigm. Anat Rec, 302:378-380, 2019. © 2019 Wiley Periodicals, Inc.