A group of viruses that use DNA as their genetic material. Herpesviruses include herpes simplex viruses 1 and 2 (HSV-1 and -2), varicella zoster virus (VZV or HHV-3), Epstein-Barr virus (EBV or HHV-4), cytomegalovirus (CMV or HHV-5), herpes simplex viruses 6 and 7 (HSV-6 and -7), and Kaposi sarcoma herpesvirus (KSHV or HHV-8).