NightMare

NightMare is a screamer scareware program that was distributed on the Amiga Disks (Fish #448). It is widely regarded as the first scareware program of its kind. created by Patrick Evans who at the time, lives in Nobleton, Ontario, Canada, when the malware was first created, and it was free to redistribute, with source code available from the author.

If the person executes the code "Nightmare" in the Amiga Disk Operating System (DOS), it runs in the background every 5 minutes. The screen will then cut to an image of a skull from the right side, his mouth open, teeth covered in blood, and a bullet hole in his back from which blood was leaking, lasting for four fifths of a second, accompanied by a resonant shriek which echoes out.

Links
NOTE: The following video contains a screamer!
 * youtube.com/watch?v=ubFGj4lQSyM