One of the most "popular" viruses was WDEF. I don't remember what it did, but it wasn't much whatever it did. If your Mac was infected, then SAM, Central Point Antivirus, Disinfectant, or whatever cleaned your system as good as new.Back in the old Mac Plus days there were things like NVIR etc. I never found one that actuaslly did anything. They alll seemed to have 4 letter names.
Just a historical note: Most Mac viruses date back to System 6 and the early days of System 7. By the time MacOS 8 was released, the number of new Mac-exclusive viruses was down to fewer than one per year. MacOS X reduced that number to zero.