The first known computer virus appeared in 1971

“Theory of self-reproducing automata”, the first known computer virus appeared in 1971 and was dubbed the “Creeper virus”. This computer virus infected Digital Equipment Corporation’s (DEC) PDP-10 mainframe computers running the TENEX operating system. The Creeper virus was eventually deleted with a program known as “The Reaper” created by Ray Tomlinson. Some people consider “The Reaper” the first antivirus software ever written – it may be the case – but it is important to note that the Reaper was actually a virus itself specifically designed to remove the Creeper virus.