PuTTY - Popular free terminal application. Mostly used as an SSH client.
Lynis - Security auditing tool for systems running Linux, macOS, BSD, and other UNIX-based systems.
MobaXterm - Enhanced terminal for Windows with X11 server, tabbed SSH client, network tools and much more
Silverback - Silverback 3
iTerm2 - A terminal emulator for macOS that does amazing things.
Chkrootkit - Chkrootkit is a Linux tool to locally check for signs of a rootkit. It contains: