Who created the first self-replicating program known as the Creeper in 1971?

Bob H. Thomas created the first self-replicating program known as Creeper in 1971.

Thomas developed Creeper while working at BBN Technologies for the ARPANET, an early packet-switched computer network. The experimental program moved between DEC PDP-10 computers and displayed the message, “I’m the creeper: catch me if you can!” It was designed as a demonstration, not as destructive criminal malware.

Creeper is often described as the first computer worm because it could copy itself across a network. The distinction between a worm and a virus is that a worm is generally self-contained and spreads across networks, while a virus usually attaches itself to another file or program. Modern terminology can vary, but Creeper is a standard landmark in malware history.

A related program called Reaper was later developed to find and remove Creeper. That relationship is sometimes presented as the first antivirus example, although the broader history of antivirus software is more complicated than a single starting point.