The first ever computer virus for personal computers was called Elk Cloner, and was created and distributed on an Apple II computer, 25 years ago, in 1982.
(It was created by a 15-year-old called Richard Skrenta. It didn't do any damage, it just displayed the following message:
Elk Cloner: The program with a personality
It will get on all your disks
It will infiltrate your chips
Yes it's Cloner!
It will stick to you like glue
It will modify RAM too
Send in the Cloner!
You can see why he was a hacker and not a poet.)