Malwarebytes - Malwarebytes protects you against malware, ransomware, and other advanced online threats that have made antivirus obsolete and ineffective. Free Anti-Malware & Malware .

Lynis - Security auditing tool for systems running Linux, macOS, BSD, and other UNIX-based systems.

Panda Antivirus for Mac - A bare bones malware and anti-virus scanner.

Silverback - Silverback 3

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.

Chkrootkit - Chkrootkit is a Linux tool to locally check for signs of a rootkit. It contains: