RobotLib

RobotLib is SCR's custom robotics library, and is really useful for handling low level robotics tasks, like moving a motor or reading an encoder.
RobotLib is currently written in C and targets the Arduino platform. In the future it may be expanded to cover other boards as well
RobotLib can be cloned from the SCR repos here: GitHub - Sooner-Competitive-Robotics/RobotLib: A library of...

ArduinoJson

ArduinoJson is really a useful library if your application needs to parse or encode JSON on an arduino. The library has a lot of support and documentation.
More information about ArduinoJson can be found here: ArduinoJson: Efficient JSON serialization for embedded C++

Adafruit TiCoServo

If your servo is twitching and you are using LED lights on your robot, this library helped a lot with reducing the twitching: The TiCoServo Library | Using NeoPixels and Servos Together...

Arduino Library List

A list of all arduino libraries can be found here: https://www.arduinolibraries.info/