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Creeper and Reaper

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Creeper was the first computer worm, while Reaper was the first antivirus software, designed to eliminate Creeper.


Creeper and Reaper
TypeComputer worm[1]
AuthorsBob Thomas
Technical details

Creeper was an experimental computer program written by Bob Thomas at BBN in 1971.[2] 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.[3] This self-replicating version of Creeper is generally accepted to be the first computer worm.[1][4] Creeper was a test created to demonstrate the possibility of a self-replicating computer program that could spread to other computers.

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"[5][4]


Creeper had a minimal impact on the computers it infected. No more than 28 machines could have been infected, as that was the number of machines running the TENEX operating system on ARPANET.[6] The operators of the machines were also collaborators in the project, and Tomlinson needed permission to run the program on their machines. In an interview, Tomlinson also stated that there were no unintended effects from running the program.[6]


Original author(s)Ray Tomlinson
Initial release1972
Operating systemTENEX

Reaper was the first anti-virus software, designed to delete Creeper by moving across the ARPANET. It was created by Ray Tomlinson in 1972.[3]

Cultural impact[edit]

The conflict between Creeper and Reaper served as inspiration for the programming game Core War,[3] while fictionalized versions of Reaper have been used as antagonists in the anime Digimon Tamers[7] and the visual novel Digital: A Love Story.[8] A humanized Creeper has also appeared in the webcomic Internet Explorer, alongside the likewise personified Morris Worm.[9]


  1. ^ a b IEEE Annals of the History of Computing. Vol. 27–28. IEEE Computer Society. 2005. p. 74. [...]from one machine to another led to experimentation with the Creeper program, which became the world's first computer virus: a computation that used the network to recreate itself on another node, and spread from node to node. The source code of creeper remains unknown.
  2. ^ Thomas Chen, Jean-Marc Robert (2004). "The Evolution of Viruses and Worms" (PDF). Retrieved 31 July 2019.
  3. ^ a b c John Metcalf (2014). "Core War: Creeper & Reaper". Retrieved 1 May 2014.
  4. ^ a b From the first email to the first YouTube video: a definitive internet history. Tom Meltzer and Sarah Phillips. The Guardian. 23 October 2009
  5. ^ Sahay, Manish (January 2023). "The History of the First Computer Virus on Windows, Mac, and Linux". thepcinsider.com. Retrieved 16 June 2022.
  6. ^ a b "Interview with Ray Tomlinson on Creeper/Reaper – OSnews". www.osnews.com. Retrieved 17 January 2024.
  7. ^ "Chronicle, The Background History". konaka.com.
  8. ^ Christine Love (February 2010). Digital: A Love Story. *Blue Sky: When Mother realized the mistake it had made, *Reaper was created to combat the self-replicating mess it had created, and fabricated the story about a "creeper virus" in order to obfuscate the matter to human observers.
  9. ^ "Internet Explorer – Ep. 50 – Creeper". webtoons.com. Retrieved 1 August 2022.