Since the seminal studies involving bacteriophages, the DNA viruses have fascinated the scientific community. DNA viruses were essential not only for the understanding of viral biological process, but also were a fundamental tool for the discovery and expanding knowledge related to cellular processes, such as transcription, translation, DNA repair, glycosylation and others. DNA viruses were also important characters during human history and evolution. The lethal and terrifying infection caused by a DNA virus, the smallpox disease caused by the variola virus, shaped and defined patterns of human migration, societies' interactions and raised innovative public health measures. In recent decades, some DNA viruses have been used as tools for heterologous protein expression and delivery, improving the field of vaccinology and diagnosis. In addition, some years ago, the discovery of the first mimiviruses shed new light on the study of DNA viruses field. Since then, many interdisciplinary studies, from distinct research groups, revealed breath-taking and controversial data regarding the origins, evolution and ecology of large and giant viruses. In this Research Topic, we received contributions from several colleagues on a broad range of topics related to large and giant DNA viruses.