Termux - a terminal emulator application for Android OS extendible by variety of packages.

A Simple android remote administration tool using sockets. It uses java on the client side and python on the server side

Termux add-on app which exposes device functionality as API to command line programs.

AndroRAT | Remote Administrator Tool for Android OS Hacking

Termux add-on app for integration with Tasker.

Android Penetration Tool [ RAT for Android ]

[Android RAT] Remotely manage your android phone using PHP Interface