Best answer: Though Windows malware doesn't affect Mac devices, it's easy to unknowingly send these threats to PC-using colleagues, family members, and friends. During our testing, we used live malware and saw that the protections that come with Mac devices don't always stop them. Several threats are disguised to look like legitimate Mac programs and often sneak in through email messages and network connections. Luckily, a good antivirus program can stop them while keeping your Mac safe.Staff pick: Bitdefender Antivirus for Mac ($60 at Bitdefender)Tech support recommended: Malwarebytes ($40 at Malwarebytes)Free Mac antivirus: Avast Essential Security for Mac (Free at Avast)