Malwarebytes - Malwarebytes protects you against malware, ransomware, and other advanced online threats that have made antivirus obsolete and ineffective. Free Anti-Malware & Malware .
Avira - Cloud based email security solution
Clam Xav (desktop) - Specifically with Clam Xav Sentry configured to scan inserted disks.Please read global comments on this question for an explanation of why desktop apps are being recommended for virus detection on ios devices.
CleanMyMac X - Clean, protect and speed up your Mac
Ad-Aware Free Antivirus+ - Ad-Aware Free Antivirus+ is a world’s most leading security solution that gives you comprehensive malware protection with real-time monitoring, threats alerts and automatic updates you can rest easy knowing that you are protected.
Microsoft Security Essentials - Microsoft Security Essentials is Microsoft's own foray into the world of virus protection.