The IT Facts

Creeper was an experimental computer program written by Bob Thomas at BBN in 1971. Its original iteration was designed to move between DEC PDP-10 mainframe computers running the TENEX operating system using the ARPANET, with a later version by Ray Tomlinson designed to copy itself between computers rather than simply move. This self-replicating version of Creeper is generally accepted to be the first computer virus.

The program was not actively malicious software as it caused no damage to data, the only effect being a message it output to the teletype reading "I'm the creeper: catch me if you can".