Early 90s Mac freeware anti-virus program
Disinfectant was a popular freeware antivirus program on the Mac from the 80's until its official retirement at version 3.7.1 in 1998:


  Announcement and Press Release May 6, 1998 
  Updated: October 11, 1998
  I regret to announce that I am officially retiring Disinfectant, our free
  anti-viral utility for the Macintosh. The current version 3.7.1 is the last
  version. Disinfectant will not be updated for the new Autostart 9805 worm or for
  any future viruses, worms, or other Macintosh malware.


It's the last antivirus I've used on my Macs. There hasn't been much need.