This chapter focuses on the emerging and less common viruses that cause encephalitis and seizures. It presents emerging encephalitides such as Japanese encephalitis virus, West Nile virus, Nipah virus, enterovirus 71, dengue virus, human herpesvirus 6, Chandipura virus and Monkeypox virus. The chapter discusses the other uncommon encephalitides such as rabies, Tick-borne encephalitis, LaCrosse encephalitis, St. Louis encephalitis, Western equine encephalitis, Eastern equine encephalitis and Murray Valley encephalitis. Most viral infections of the central nervous system cause acute brain parenchymal inflammation with perivascular lymphocytic and mononuclear cell cuffing and infiltration, ballooning and death of neurons leading to subsequent gliosis. Tick-borne encephalitis virus first infects the Langerhans cells before invading the lymphoid and reticulo endothelial system, and finally causes inflammation not just in the brain, but also in the spinal cord and the leptomeninges. The Venezuelan and Eastern equine viruses, Nipah and Hendra viruses cause widespread vasculitic changes and microvascular infarcts.